This Rare Friday the 13th

Juha-Matti Laurio writes to point out a Washington Times story about how special this particular Friday the 13th is. The digits in the numerical notation for the date add up to 13 — whether you write it in the US or the European form. From the article: "The phenomenon hasn't happened in 476 years, said Heinrich Hemme, a physicist at Germany's University of Aachen who crunched the numbers to find that the double-whammy last occurred Jan. 13, 1520."

Comments

I Just Knew I Shoulda Stayed In Bed Today

[ackthpt]

While the sum of 2+6+1+1+3=13 is mildly interesting, I never thought much about Friday the Thirteenth outside of Pogo strips. Walt kelly's character in the strip, Churchy LaFemme perhaps more than any other source kept the Friday the Thirteenth fear alive as the turtle fled in horror for decades, long before the series of films arrived. For those of us who remember (and in some cases still read) the strip, it's still a source of amusement.

"Don't shoot! Don't shoot! It's Friday the thirteenth! Very unlucky to get shot on Friday the thirteenth!"

2+6+1+1+4=14, so there goes Saturday the 14th too.

Re:I Just Knew I Shoulda Stayed In Bed Today

[stfvon007]

Near where I live a lot of people did just that cause there was so much snow, and they couldnt even get out of their driveways (not to mention branches and power lines everywhere). Never seen a snowstorm this early before. It took out quite a few trees cause the snow piled on their leaves (wich have only barly started to change color and nowhere near falling off yet)

Re:I Just Knew I Shoulda Stayed In Bed Today

[yo_tuco]

I wonder if Heinrich Hemme's calculations take into account the 10 missing days in the Gregorian calander between 4 October and 15 October 1582?

Re:I Just Knew I Shoulda Stayed In Bed Today

[enjerth]

Yeah, and it's amazing that it still adds up to 13 if you switch the numbers around, 1+1+3+2+6 = 13. WOW!

Re:I Just Knew I Shoulda Stayed In Bed Today

[Iron Condor]

Vaguely more interesting and almost veering ON topic for slashdot, in binary notation todays date would be

1010 1101 11111010110

...which just so happens to have thirteen "1"s in it.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Tim Browse]

How would his calculations take this into account?

There was no 13th October 1582, so it's irrelevant.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Anonymous Coward]

"todays [sic] date would be"

Hum, you could say a date also includes time. The start of today is JD2454021.5 and at noon is JD2454022.0. That is, if you convert these Julian dates back to Gregorian date you have a fraction of a day to deal with. You'll need floating point.

Re:I Just Knew I Shoulda Stayed In Bed Today

[attonitus]

I think that the point of the GP is that it changes when the Fridays are.

Re:I Just Knew I Shoulda Stayed In Bed Today

[enjerth]

My comment was not off-topic. The original post suggests that, by coincidence, the numbers of todays date add up to 13 in both US and European notation, which happens to be just a difference of order.

I was astonished that people actually grasp that gem of mathematical truth.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Anonymous Coward]

"There was no 13th October 1582, so it's irrelevant"

13 October 1582 (Julian) exists.

Re:I Just Knew I Shoulda Stayed In Bed Today

[StormReaver]

"Yeah, and it's amazing that it still adds up to 13 if you switch the numbers around, 1+1+3+2+6 = 13. WOW!"

Unless you get an old COBOL programmer to sum them up for you, in which case you get 11:

06+10+13 = 11

But then the results aren't as fun, which is the life story for COBOL programmers -ducks-.

Re:I Just Knew I Shoulda Stayed In Bed Today

[AstrumPreliator]

And the hex representation is...

A D 7D6

If you read it like "ADD 7 6" you get 13. I'd look for more examples but I just don't really care. If you're looking for something you will find it everywhere, regardless of what you're looking for.

That is of course unless it's your keys and you're late for work. ad7d6

Re:I Just Knew I Shoulda Stayed In Bed Today

[MP3Chuck]

Also interesting is that the UNIX timestamp, in binary, also contains 13 1's:

C:\php5>php -r "echo decbin(strtotime('13 Oct 2006'));"
01000101001011110000111101000000

Re:I Just Knew I Shoulda Stayed In Bed Today

[Anonymous Coward]

1+1+2+3+6 = 13.

1

1+1 =2

1+2 = 3

1 + 2 + 3 = 6

1 + 2 + 3 + 6 = 13! ...

Toodles!

[record with a skips(i) or skips(i+n) or ... as long as the header has the i and n.
don't forget the {if}]

Re:I Just Knew I Shoulda Stayed In Bed Today

[SnarfQuest]

It depends on where you are. Different countries changed over at different dates. And some places use different calendars yet.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Bardez]

I sure as hell didn't see it coming, but after.... wow (holy shit!), 13 hours of consciousness, my really great day turned really shitty really fast. 13s abound, it seems.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Iron Condor]

The start of today is JD2454021.5 and at noon is JD2454022.0

Which, if my rusty astronomy serves, would make it MJD54022, right?

5+4+2+2=13 You can't make this shit up...

Re:I Just Knew I Shoulda Stayed In Bed Today

[AJWM]

They were only missing in the Catholic world. In England and colonies they didn't switch until 1752, skipping from Sept 2 to Sept 14, although the 13th wouldn't have fallen on a Friday in any case. (Note the extra missing day because of another 170 years of calendar slippage.)

Must have made life interesting in the world between 1582 and 1752. Talk about time zone changes. Travel from Paris to London and arrive a week before you left...

The unix/linux 'cal' program recognizes this, at least for 1752. Might be different for other countries (or different versions of cal).

Re:I Just Knew I Shoulda Stayed In Bed Today

[tgv]

And like this

0000000 1010 1101 11111010110

it also contains thirteen zeroes.

This is horrible! This must be doomsday!!

No, wait, it's the 14th already...

Re:I Just Knew I Shoulda Stayed In Bed Today

[fbjon]

I like it. This rare friday the 13th happens to be my birthday.

Re:I Just Knew I Shoulda Stayed In Bed Today

[MonoSynth]

In hexadecimal it is:

D-A-7D6

7+6=13 :)

Re:I Just Knew I Shoulda Stayed In Bed Today

[ggy]

OMG! And I just rolled 7 D6:es and got 13!

Hrm... Maybe I should quite pen'n'paper RPGs?

Re:I Just Knew I Shoulda Stayed In Bed Today

[oz1cz]

In 1520 no country had changed yet. The first countries changed in 1582.

Re:I Just Knew I Shoulda Stayed In Bed Today

[BennyBigHair]

the dates are still the same, even if the 24 hour period they refer to is a different amount of time before the present

Re:I Just Knew I Shoulda Stayed In Bed Today

[oz1cz]

I wonder if Heinrich Hemme's calculations take into account the 10 missing days in the Gregorian calander between 4 October and 15 October 1582?

Yes they did. 13 January 1520 was a Friday in the old calendar. So everything is as it should be.

Re:I Just Knew I Shoulda Stayed In Bed Today

[ari_j]

The really interesting part of the switch, to me, is the Swedish debacle. Essentially, in 1700 they set a 40-year no-leap-days plan to get on track, but ended up with leap days in both of the following leap years, so they ended up one day ahead of the Julian calendar (and still nowhere near the Gregorian calendar). They held a February 30 double leap day in 1712 to get back on Julian and then finally managed to convert to Gregorian by 1753.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Tim Browse]

Oh, I seeeee.

We can but take solace in the fact that it's all a load of horseshit anyway, so it doesn't really matter :-)

Still, to quote Bunnie from Animal Crossing: "Yaaaay! Numbers!"

Re:I Just Knew I Shoulda Stayed In Bed Today

[Directrix1]

Mine too. Friday the 13ths are awesome. But it sure seems like we don't hardly ever get any weekend birthdays.

Re:I Just Knew I Shoulda Stayed In Bed Today

[Anonymous Coward]

Also, did you notice that the name of the shtml main page is 222223, which added is 13!

Re:I Just Knew I Shoulda Stayed In Bed Today

[pnutjam]

Horsehit?
The timing belt on my car broke, it was awful. I couldn't have had anything to do with it being 110,000 miles past due on being changed. :(

Re:I Just Knew I Shoulda Stayed In Bed Today

[shaneh0]

No, that's incorrect. Days of the week remained consistent. It changes which day the 13th lies on.

Re:I Just Knew I Shoulda Stayed In Bed Today

[attonitus]

It depends on the frame of reference, i.e. if by "when the Fridays are" I meant periods of seconds before or after epoch then you're right. If by "when the Fridays are", I meant "which days of the month Fridays fall on", then I'm right. Since the context clearly points to the second interpretation, I'm right :-).

Re:I Just Knew I Shoulda Stayed In Bed Today

[shaneh0]

you're an idiot. go read wikipedia. you'll learn something

Re:I Just Knew I Shoulda Stayed In Bed Today

[attonitus]

Maybe it would help if you actually saw a calendar. In England, September 15 1752 (2 days after the change) was a Friday. If you failed to take into account the calendar change then you'd expect that September 1 was also a Friday. But it wasn't. It was a Tuesday. So the calendar change changed which day of the month the Fridays fall on.

Your move. Fool.

Re:I Just Knew I Shoulda Stayed In Bed Today

[CopaceticOpus]

I know I'm coming in late to this discussion, but I'm trying to wrap my head around how they could accidentally have a leap day in 1704 and 1708. Did they not get the memo distributed to the calendar manufacturers in time? Or did they just wake up with a terrible hangover on March 1st and say, "Oh God, please tell me we didn't do it again."

Re:I Just Knew I Shoulda Stayed In Bed Today

[ari_j]

I honestly have no idea. Forgetting to set your clocks ahead for daylight saving time is one thing, but missing an entire leap day two times in a row is kind of funny.

Commutivity

[P(0)(!P(k) P(k 1))]

From TFS:

The digits in the numerical notation for the date add up to 13—whether you write it in the US or the European form.

What a relief! I always suspected that the commutativity of addition applied on both sides of the Atlantic.

Or did they mean to imply that the dæmons who govern paraskevidekatria are too preoccupied to uphold mathematical principles today?

In a related article:

Thirteen people, pledged to eliminate triskaidecaphobia, fear of the number 13, today tried to reassure American sufferers by renting a 13ft plot of land in Brooklyn for 13 cents (10d) a month. (Daily Telegraph, 1967)

Re:Commutivity

[ackthpt]

What a relief! I always suspected that the commutativity of addition applied on both sides of the Atlantic. Or did they mean to imply that the dæmons who govern paraskevidekatria are too preoccupied to uphold mathematical principles today?

If you're in Europe, then you're in luck. It's the 14th already.

Re:Commutivity

[fuzzix]

Speaking of adding:

"The phenomenon hasn't happened in 476 years, said Heinrich Hemme, a physicist at Germany's University of Aachen who crunched the numbers to find that the double-whammy last occurred Jan. 13, 1520."

...someone can't. Or is it 1996? :)

Re:Commutivity

[UglyTool]

*sigh*

1520 + 476 = 1996...

Re:Commutivity

[Anonymous Coward]

*sigh*

1520 + 476 = 1996...

Nonono, he can't subtract. Clearly, he couldn't have known the number 476 before he computed the years. Addition has nothing to do with! ;-)

Re:Commutivity

[nebaz]

I can imagine what someone would say about the parent being 'Informative' during metamoderation. :-)

Hmm... a post showing the sum of two numbers.

Re:Commutivity

[Anonymous Coward]

I think Jan 13, 1520 may or may not be a Friday so unconditionally all over the world. It all depends on the Country due to the fact that switch to Gregarian Calader occured on 15 of October in 1582, and Jan 13, 1520 goes past the switch date, and because different countries adopted Gregarian calander on different dates.

Re:Commutivity

[Anonymous Coward]

Don't forget the Gregorian calendar started in 1582.

Re:Commutivity

[NoMaster]

... paraskevidekatria ...

Not to be confused with Alkulukuja Paskova Karhu, which also deals with the number 13...

Re:Commutivity

[Ninjaesque One]

... You can get a 13 sq. ft plot in Brooklyn for 13 cents a month?

Re:Commutivity

[donscarletti]

1520 was before the first switch date, thus everyone was using the Julian Calender therefore if Jan 13, 1520 happened on a Friday somewhere, it happened on a friday EVERYWHERE.

Re:Commutivity

[Filthysock]

1582, never forget.

Re:Commutivity

[constantnormal]

Don't take commutivity for granted.

It blew my mind to have pointed out to me (in John Derbyshire's EXCELLENT book Prime Obsession) that some infinite series sum to different values, depending upon the order in which the terms are added!

This amazing property is called "conditional convergence".

However, since we are dealing with only finite series in this instance, I think (hope) that we can assume that commutivity rules.

Re:Commutivity

[roman_mir]

1520 + 476 = 1996 - now that is +5 Interesting.

Also, from the +5 Interesting department:

1111 + 2222 = 3333
1010 + 101 = 1111

and not to forget the classics

7 * 6 = 42

Re:Commutivity

[WilliamSChips]

That last one is 6*9=42, not 6*7=42. Sheesh, haven't you read the books?

Re:Commutivity

[roman_mir]

So what you are saying is that position 6*9 is the ultimate question to the ultimate answer? It is so obvious now.

Re:Commutivity

[UglyTool]

I really, REALLY hate responding to myself, especially when it's for as stupid a reason as this...

If you'll look to the parent of my original post, and then to the parent of that post, and work your way down, it really does make perfect sense.

The post quoted TFA as saying this hadn't happened in 470 years, and then mentioned that it should be 1996 then. The responder completely missed this point, however, and went on to state that he could, indeed, add numbers to make 13. The post to which he was responding pointed out that, when adding 1,520 and 476, you indeed get 1,996

I apologize for not making some snarky comment about this in my original post.

Can I get back to Runescape now? I'm killing Iron Dragons, and you *know* how much they hate waiting!

Re:Commutivity

[Anonymous Coward]

In *gasp* base 13!!

Re:Commutivity

[WilliamSChips]

"What do you get when you multiply six by nine", and then Arthur Dent ran out of Scrabble tiles.

Re:Commutivity

[goeldi]

1520 + 476 = 1996...

And most important, if you live in the year 2009, then you are 13 years away from 1996!

coincidence? I think not!

[foobari]

*places foil hat on head*

Of course, you care about that only if

[Rosco P. Coltrane]

you're a numerologist, a mystic, a fortune teller or a similar quack. For most other people who happen to be superstitious, it's just another Friday the 13th. And for the rest of us, the overwhelming majority of rational folks, it's just another day...

Re:Of course, you care about that only if

[ackthpt]

you're a numerologist, a mystic, a fortune teller or a similar quack. For most other people who happen to be superstitious, it's just another Friday the 13th. And for the rest of us, the overwhelming majority of rational folks, it's just another day...

I kept getting cut off by slower vehicles pulling into my lane on the way to work. (They weren't passing anyone, they just moved into it for no apparent reason.) Then I found a dead fly in my salad at lunch (OK, some people might consider it luck, finding it rather than half of one on the next fork.)

Still, haven't been hit by a falling meteor, so far so good.

Re:Of course, you care about that only if

[Iron Condor]

And for the rest of us, the overwhelming majority of rational folks, [...]

Wow.

What country do you live in?

Can I come?

Re:Of course, you care about that only if

[Anonymous Coward]

, the overwhelming majority of rational folks,

who the fuck are you trying to kid?

Re:Of course, you care about that only if

[jafac]

Yeah, but a thunderstorm killed my build server this morning, including the backup drive.

Usually not superstitious.

But this Friday the 13th sucked rocks.

Re:Of course, you care about that only if

[Anonymous Coward]

At my first job, we were paid on the 15th and last of the month. It was always on a business day, so I was always paid on Friday the 13th when the 15th was on Sunday. I always though that Friday the 13th was a good day. :)

Re:Of course, you care about that only if

[MollyB]

IANAN (I am not a numerologist), but what little I've picked up suggests that "13" is not particularly interesting, save for the fact that the digits add up to 4. I've no clue as to the mystic value of four. Tarot fans can perhaps illuminate this arcane subject...

Re:Of course, you care about that only if

[bladesjester]

Well, if you follow Chinese beliefs, the number 4 is unlucky because the word sounds similar to the word for death (they just use different tones).

13th Post!

[markana]

sorry....

Re:13th Post!

[rolfwind]

Yep, you hit it. I viewed at -1 Flat, and counted, you are indeed the 13th post.

Congratulations. You have reached the pinnacle of your life.

Re:13th Post!

[geekoid]

"Congratulations. You have reached the pinnacle of your life."

are you kidding me? tomorrow he could be the 14th post.

Re:13th Post!

[4D6963]

are you kidding me? tomorrow he could be the 14th post.

And then? Tomorrow will be the 14th anyway..

Re:13th Post!

[Firehed]

Are you kidding? He's gotta pull off a stunt like that twelve more times. And, for that matter, tweleve more times today.

Pffft....

[yo303]

It's bad luck to be superstitious.

yo.

Re:Pffft....

[ackthpt]

It's bad luck to be superstitious.

T'is better to be a Roman. X + X + I + I + I + M + M + V + I = MMXXIX

paraskevidekatriaphobics - a new word

[xmas2003]

The article mentions that the Fear of Friday, the 13th is called Paraskevidekatriaphobia ... Google only has 1,650 results with Urban Legends the first one. I gotta believe a double whammy for those superstitious people to have it fall on Halloween - D'OH! ;-)

Re:paraskevidekatriaphobics - a new word

[mattmacf]

Halloween, however, is celebrated on October 31, therefore, it's only superstitious for those crazy Europeans who insist on writing the date backwards.

; D

Re:paraskevidekatriaphobics - a new word

[commodoresloat]

I'm a little unclear as to how Friday the 13th could fall on October 31st?

On another note, that urban legends article is pretty interesting; it cites a study from the British Medical Journal that claims that although the number of people driving goes significantly down on a friday the 13th, the number of accidents goes significantly up. Anyone know anything about this study, or if anyone has tried to replicate these disconcerting results?

On another note, I fell down half a flight of stairs today -- stairs I have never fallen down before, despite using them at least 3 times a week. My friend got a flat tire. This anecdotal evidence proves... well, nothing, but I'm still interested in that study.

Re:paraskevidekatriaphobics - a new word

[xmas2003]

I meant to say NEAR (not on) Halloween - although ironically, 31 is 13 flipped ... so just read it backwards! ;-)

Sorry 'bout the typo.

Re:paraskevidekatriaphobics - a new word

[AcidArrow]

It's not a new word. Even though I never heard of it before, I happen to be Greek.

Paraskevi = Friday
Dekatria = Deka Tria = ten three = thirteen
Phobia well... You know that word, but what you probably didn't know is that it's the same in Greek

(please note, since the Greek alphabet is different than the latin one, the words are spelled in a way to 'sound' or 'look' okay in Greek. It's actually in a language called Greeklish, the internet language of greeks for communicating through applications that don't support the Greek alphabet)

Seatching for the origin of the word I found this :

Definition of Paraskevidekatriaphobia
Paraskevidekatriaphobia: Fear of Friday the 13th.
The word "paraskevidekatriaphobia" was devised by Dr. Donald Dossey who told his patients that "when you learn to pronounce it, you're cured!"

Re:paraskevidekatriaphobics - a new word

[Brad1138]

10/31/2006 1+3+1+2+6=13 could be an extra spooky Halloween!

the commutivite property of addition...

[kylemonger]

... is taught in grade-school. Surely you don't expect anyone fascinated by numerology to remember it now... ?

A physicist?

[nickmue]

They needed a physicist to figure out the last time that happened?? Couldnt most first year CS majors write a program to calculate this??

Re:A physicist?

[robi2106]

No. It is just that a physicist is the only type of person taht would sit there and think "I wonder when this happened last....."

jason

Re:A physicist?

[Anonymous Coward]

I think the point was that you don't even need to be a first year CS major to calculate this.

Re:A physicist?

[Iron Condor]

Here's a cute little first-year CS problem: show that with the current calendar the 13th of a month has a higher probability of falling on a friday than any other day of the week.

Re:A physicist?

[FuturePastNow]

They should have just found an autistic guy.

Re:A physicist?

[Anonymous Coward]

You don't know the CS grads I work with - many of them would have trouble writing a program to display the current date...

Re:A physicist?

[networkBoy]

I dunno. I'm just a tech and when my daughter was born I noted that she was born on Friday the 13th on a full moon, so I wondered:
"gee I wonder how often that the 13th is a Friday and a full moon?"
Answer? 11
For whatever reason I thought that was pretty cool, so her 11th and 22nd birthdays are going to be huge, her 33rd likely se will want to ignore :-)
-nb

Re:A physicist?

[buntklicker]

You only need a calendar to see that it last happened on January 13, 2006. Yes, exactly nine month ago.

In other words ...

[vlad_petric]

Most of us don't suffer from Triskaidekaphobia

Re:In other words ...

[intangible]

Though I seem to know quite a few who suffer from Hexakosioihexekontahexaphobia

European Dates

[RAMMS EIN]

``The digits in the numerical notation for the date add up to 13 whether you write it in the US or the European form.''

That may be related to the fact that they are the same digits, only in a different order.

By the way, there isn't really such a thing as a "European form". Different European countries have different conventions about writing dates.

Re:European Dates

[Anonymous Coward]

well, maybe so, but to an american, anything non-american is "european". which also means randomly different, but not so much that it matters unless you are also european yourself.

sorry -- americans are like that.

Re:European Dates

[MrWhitefolkz]

Thanks for speaking for all Americans...

Re:European Dates

[orangepeel]

"Give me ISO 8601 or give me death!"

Re:European Dates

[mr_matticus]

US notation is standardized MM/DD/YY. I personally write "13 October" on all of my meeting notes, etc. but the short form is still always MM/DD/YY. It's assumed and engrained in forms, computer input fields, etc. If you've been using DD/MM/YY on government forms you may find yourself in trouble!

Re:European Dates

[isorox]

US notation is standardized MM/DD/YY

Which is just plain dumb. yy(yy)/mm/dd -- most significant first, is the best choice, but otherwise dd/mm/yy (least signficant first) is the next option. mm/dd/yy makes as much sence as yy/dd/mm, it's a random order.

Re:European Dates

[mr_matticus]

Oh I agree completely, but that's the way it is. I also think time zones and DST are ridiculous concepts. But that's all about as likely to change as the American flag. Look at US resistance to metric. Nothing needs to make sense here, it just has to be accepted by most people. It's basically Slashdot groupthink on a continental scale.

Re:European Dates

[eldepeche]

You think time zones are ridiculous concept?

Re:European Dates

[oojah]

In what way are time zones ridiculous? We could have one time zone for the whole world but I can't help thinking that would be more confusing.

DST? Well it certainly makes sense where I live which is in the Midlands of England, but I'm quite willing to accept that it makes less sense elsewhere.

As for going metric, start with something positive - moving to a more useful paper format (see http://www.cl.cam.ac.uk/~mgk25/iso-paper.html ). It's immediately useful to everyone in the US and once "Letter" is no longer the default paper size on printers/software the rest of the world will rejoice as well. As far as everything else goes, keep it. I'm quite happy knowing my height and weight in feet and stones respectively and much prefer miles to kilometres.

Re:European Dates

[isorox]

But that's all about as likely to change as the American flag

Happens a lot more than most flags. Last happened in 1960,

Re:European Dates

[WilliamSChips]

He means the basic structure of the American flag. You know, the Star-Spangled Banner which has been in use since the Revolutionary War?

Re:European Dates

[rubycodez]

citizen 34895205984, your wish has been granted, report to room 101!

Re:European Dates

[mr_matticus]

Right. Not the number of stars.

Re:European Dates

[mr_matticus]

It wouldn't be more confusing (except during the hypothetical transition period, were we to change). Times are arbitrary sets of numbers--it's actually the same absolute time everywhere in the world. Everyone basically already normalizes to GMT to communicate and conduct business; having the "local time" is an extra layer of complication based solely on an antiquated notion that "noon" should be in the rough middle of the daylight.

The only real difference is that the "business day" would not be 8-5 around the world anymore, but would vary. You might grow up in a place where it was 1000-1900, for example. As it stands now, if I need to call an associate in Tokyo, I have to find out what time it is there and convert to determine that I should call between 1400 and 1600 my time.

If we had one global time zone, I'd still need to know that I should call between 1400 and 1600, so it doesn't make it any harder to conduct business; but instead of my associate saying "I have a filing deadline at 3" and having to calculate how much time that gives me on my side of the world, he could just say "1900" and I'd know immediately how much time I had to get work done on my end. You have the added advantage of not having to adjust your watch when you cross state lines and not having to do conversion math because airplane times are given in local time zones.

It's unusual for us to think that sunset might be at 1400, because we've grown up on a time system fixed on putting 1200 in the approximate middle of daylight around the world--it made sense with a localized economy and small civilizations. It is not the best way to conduct a global society, though.

Re:European Dates

[Detritus]

The problem is that if you go to the average office supply store in the US, you will not find a single sheet of A4.

Mod Parent Down

[s-gen]

Just to prove to him its not his lucky day.

E/kdawson

[Anonymous Coward]

Isn't this supposed to be under the Enlightenment topic?

How about something more interesting?

[winkydink]

Like it's the anniversary of the supposed origin of Friday the 13th being unlucky? October 13, 1307

Every number/date/etc. is unique somehow

[burndive]

If you find one that isn't, then it's unique in being the first one that isn't.

Re:Every number/date/etc. is unique somehow

[Anonymous Coward]

And the original one is the first that was, but isn't any more?

European form

[JHromadka]

What about the African form? ;)

Re:-1, Who Cares

[sgt_doom]

Perhaps not to you but Jan. 13, 1520 was the date of Johann Gutenberg's last solid crap....not something to be taken lightly, historically speaking that is....

self-promoting talking head?

[vague_ascetic]

"But it's not exactly TGIF for the 21 million Americans who fear the day. Some may not travel or even get out of bed, said Donald Dossey, a North Carolina psychologist who coined the term "paraskevidekatriaphobia" 20 years ago. He estimates that the nation is out $900 million in lost productivity because of Friday the 13th sick-outs."

How do they come up lost productivity statistics anyway?

Re:self-promoting talking head?

[Anonymous Coward]

By my calculation $457.3 billion dollars are lost in productivity annually by calculating lost productivity statistics.

(You don't want to know the number for making obvious jokes on slashdot).

Re:self-promoting talking head?

[SnarfQuest]

How do they come up lost productivity statistics anyway?

Add digits of $900 million and Friday the 13th, and you get 13! See, there is your proof!

Um.. not so phenomenal?

[Anonymous Coward]

Hasn't anyone noticed by now that this year, there was a Friday the 13th in January, which has the exact same digits as today? (01/13/2006 vs 10/13/2006)
Meaning.. this phenomenon has happened within the last year?

Re:Um.. not so phenomenal?

[suv4x4]

Hasn't anyone noticed by now that this year, there was a Friday the 13th in January, which has the exact same digits as today? (01/13/2006 vs 10/13/2006)
Meaning.. this phenomenon has happened within the last year?

Parent is right: 01/13/2006 was a Friday. You may wanna mod the dude up.

Not that it matters either way, but this omission further proves that fatalysts and numerologists are quite slow mentally.

Re:Um.. not so phenomenal?

[daveo0331]

Also Friday, March 13, 2004

But it won't happen again until January 2024.

What makes these uncommon is that the digits in the year can't add up to more than 8. Obviously this condition is difficult to meet late in a century, which explains the gap from 1520 to 2004.

Re:Um.. not so phenomenal?

[Anonymous Coward]

Correct indeed
January 13, 2006 was a Friday, and its digits add up to 13 just like October 13, 2006.

Re:Um.. not so phenomenal?

[howlingfrog]

Grandparent: Hasn't anyone noticed by now that this year, there was a Friday the 13th in January, which has the exact same digits as today? (01/13/2006 vs 10/13/2006) Meaning.. this phenomenon has happened within the last year?

Parent: Parent is right: 01/13/2006 was a Friday... this omission further proves that fatalysts and numerologists are quite slow mentally.

Furthermore, 2006-1520 = 486, not 476. Quite slow indeed. It's fun to blame the universe for everything that goes wrong all day when there's a Friday the 13th, but people who take the whole thing seriously should be shot in the face with a bazooka.

Re:Um.. not so phenomenal?

[Samurai Cat!]

But it won't happen again until January 2024.

Ehhh! Wrong.

05/13/2011. :D

Re:Um.. not so phenomenal?

[telbij]

March 13, 2004 was a Saturday.

Re:Um.. not so phenomenal?

[suv4x4]

It's fun to blame the universe for everything that goes wrong all day when there's a Friday the 13th, but people who take the whole thing seriously should be shot in the face with a bazooka.

You better do it today, while they are weak!

Re:Um.. not so phenomenal?

[bcat24]

But don't shoot them today! That would just convince more people that Friday the 13th is unlucky.

Re:Um.. not so phenomenal?

[Anonymous Coward]

You're a Saturday!

Re:Um.. not so phenomenal?

[JohnFluxx]

They were so unlucky that they got the sums wrong!

Re:Um.. not so phenomenal?

[Archibald Buttle]

Besides there not being a Friday 13th March 2004 (as has already been pointed out, there's also no Friday 13th January 2024. Both are Saturdays.

Re:Um.. not so phenomenal?

[schlumpf_louise]

Doroteya?

Re:Um.. not so phenomenal?

[n0dna]

TFA noticed it.

Re:Um.. not so phenomenal?

[telbij]

Your mom's a Saturday!

aahh..but

[geekoid]

if it affects how other people behave, then it affects you.

Re:aahh..but

[Nimey]

That's actually my rationale for maybe believing in deities -- they may not exist in any objective sense (I'm agnostic), but other people believe in them, so their behavior is affected, which in turn affects me.

10 + 13 + 2006 = 2029...these add up to 13 too!!

[Cobraman]

10+13+2006 = 2029 2+0+2+9 = 13 aaaaaaaaaaaaaaaaaaaaaaaaaaaahhhh! all hell is breaking loose!!!!!!!

Scheiße!

[suso]

I always confuse Halloween and Christmas.

- Octo Weinstein

Re:Scheiße!

[Kredal]

Well, of course... because Dec 25 = Oct 31

(decimal and Octal, that is)

Re:Scheiße!

[dotgain]

Thanks for carefully explaining that to us all.

WTF??

[Harmonious Botch]

Did the editor forget that this /.? How is this superstition news for geeks?

Re:WTF??

[SeaFox]

How is this superstition news for geeks?

We're supposed to use it to take advantange of those of lower intelligence. The more information we have about superstitions the easier it is to use it against someone.

Re:WTF??

[Anonymous Coward]

Obviously you have never supported any major systems. I used to pray every time I restarted a Windoze box. And I'm a freaking atheist.

Re:WTF??

[WilliamSChips]

There are no atheists running Windows systems...

Old news!

[Eythian]

Slashdot is behind the times again! According to all my calendars, it's been Saturday the 14th for 13 hours already :)

Re:Old news!

[geekoid]

ha, when I go home, your weekend will be half over, while mine is just getting started.

Also, I get three days off every weekend.

That had nothing to do with the subject, but I love to brag about that.

Re:Old news!

[smoker2]

Ah you crazy kiwis, always out there on the bleeding edge ....

Re:Old news!

[isorox]

Slashdot is behind the times again! According to all my calendars, it's been Saturday the 14th for 13 hours already :)

Lucky you

The first Friday the 13th..

[the_rajah]

On Friday, October 13, 1307 (a date possibly linked to the origin of the Friday the 13th legend), Philip had all French Templars simultaneously arrested, charged with numerous heresies, and tortured by French authorities nominally under the Inquisition until they allegedly confessed. This action released Philip from his obligation to repay huge loans from the Templars and justified his looting of Templar treasuries. From http://en.wikipedia.org/wiki/Knights_Templar

Re:The first Friday the 13th..

[SGI-Batman]

...that's the proof you really enjoyed 'The Da Vince Code'. As a matter of fact we stupid European's (writing dates STILL backwards) learn about this in school when we're about 10-12 ys old (depends of the country's stupidness we live in). ;-) Cheers Ralf

Re:The first Friday the 13th..

[witte]

Inspector Colombo says 'follow the money.'

Re:-1, Who Cares

[Anonymous Coward]

Hey, could be worse. At least it's timely.

When the dupe appears next Tuesday, it'll just be sad.

- K

"Pure chance,"

[Scooter]

From TFA:-

'"Pure chance," the good professor told the press yesterday. '

Er right then, and there was me thinking the dates were pretty much predictable. I have a sort of flip chart thing on my wall that has successfully predicted all the dates this year - in sequence! It has pictures of cars on it too, which is nice.

Re:"Pure chance,"

[geekoid]

he is a physist.
Clearly he was talking about the existence of the universe that has linear time that has life that creates a calendar was pure chance.

Re:-1, Who Cares

[geekoid]

niether is your post, yet you still posted it.

African dates are non-migratory (n/t)

[Mateo_LeFou]

no text

That's "31" Backwards

[Doc Ruby]

And what Friday the 13th could be creepier than one in October?

The Catholics who made our modern calendar had a wicked sense of humor.

Unlucky my ass..

[MioTheGreat]

Unlucky my ass. I was #7 for preordering my Wii this morning....

Re:Unlucky my ass..

[earthbound kid]

Ah yes, but just wait, when you finally get it, your Wii will turn out to be haunted by giant crabs from historical Japan which you can hit the weak point of for massive damage. Spooooooky.

(I was number 21 of 21 Wiis at my store. My lucky day?)

The Math?

[Anonymous Coward]

"The phenomenon hasn't happened in 476 years, said Heinrich Hemme, a physicist at Germany's University of Aachen who crunched the numbers to find that the double-whammy last occurred Jan. 13, 1520."

Is it just me or does 2006-476=1530

Re:The Math?

[Anonymous Coward]

Jan. 13, 1520 = 01/13/1520 = 0+1+1+3+1+5+2+0 = 13

Birthday today

[YrWrstNtmr]

Does anyone else in here have a birthday today?

Re:Birthday today

[Anonymous Coward]

I'm sure many have a birthday today - to get an average, just divide the number of slashdot users by 365 and you'll get an approximate number of slashdot users born today. Of course, someone would argue that this is just the techy crowd so the result maybe skewed (techy people are mostly born around other months than october? .. yeah right).

Re:Birthday today

[Anonymous Coward]

yup, Damian, a friend of mine.

"Crunching" the numbers

[thisisjoel]

If anyone else wants to "crunch" those numbers, here's some Perl:

use Date::Calc qw( Add_Delta_Days Day_of_Week );

my $MAX_YEAR=3000;
my @date = (1,1,1);

sub summer { $a = 0; foreach (@_) { $a += $_ } $a }

while( $date[0] < $MAX_YEAR ) {
@date = Add_Delta_Days( @date, 1 );
if( $date[2] == 13
&& Day_of_Week( @date ) == 5
&& summer( split '', sprintf( "%04d-%02d-%02d", @date ) ) == 13
) {
printf( "%04d-%02d-%02d\n", @date );
}
}

I get 2006-01-13 as the most recent occurrence.

Re:"Crunching" the numbers

[Anonymous Coward]

I verified your findings. And Jan. 13, 1520 was a tuesday. Never ask a physicist to do the job of a computer scientist.

Here's my python:

import calendar
year = 2006
month = 10
months = ['jan','feb','march','apr','may','june','jul','aug ','sep','oct','nov','dec']

for y in range(year,0,-1):
        for m in range(month,0,-1):
                for week in calendar.monthcalendar(year,month):
                        for d in week:
                                if d == 0: continue
                                if d != 13 or calendar.weekday(y,m,d) != calendar.FRIDAY: continue
                                strDate='%d%d%d'%(d,m,y)
                                sum = 0
                                for digit in strDate:
                                        sum += int(digit)
                                if sum == 13:
                                        print "%d-%s-%d"%(d, months[m-1], y)

Re:"Crunching" the numbers

[Anonymous Coward]

The calendar changed on March 25th in 1752, so using the built in Perl/Python functions to determine day of the week from the date won't work.

A quick google reveals this little web app Web App that verifies that the date in TFA was indeed a Friday.

Re:"Crunching" the numbers

[attonitus]

Jan. 13, 1520 was a tuesday

No it wasn't. Read your documentation: "the current Gregorian calendar indefinitely extended in both directions". So your code is invalid pre-1582 (and even later if you consider that not every country adopted it immediately).

Never ask a computer scientist to do the job of an historian?

Re:"Crunching" the numbers

[SnarfQuest]

If you modify the program to use a 2 digit year, like most people write on their checks, you can get a lot of new dates to be frightened of. Of course, the conversion from julian to gregorian dates messes up the algorithm.

#!/usr/bin/perl

use Date::Calc qw( Add_Delta_Days Day_of_Week );

my $MAX_YEAR=3000;
my @date = (1,1,1);

sub summer { $a = 0; foreach (@_) { $a += $_ } $a }

while( $date[0] $MAX_YEAR ) {
@date = Add_Delta_Days( @date, 1 );
if( $date[2] == 13
&& Day_of_Week( @date ) == 5
&& summer( split '', sprintf( "%04d-%02d-%02d", $date[0] % 100,$date[1],$date[2] ) ) == 13
) {
printf( "%04d-%02d-%02d\n", @date );
}
}

Knights Templar

[Danathar]

I find it funny that people regaurd today as unlucky when it's only the Aniversary of the sacking of the Knights Templar by the King of France and the Pope hundreds of years ago!

History that still effects people after so long is cool

Re:Knights Templar

[Nimey]

You do know that all history affects us to some extent, right?

I'm not talking about the Balkans or the Middle East where what your relative did to mine seven hundred years ago is a valid reason for me killing you.

Interesting, but...

[throatmonster]

So fucking what?

Re:But isn't that really 4?

[masterzora]

Good thing Japanese culture associates 4 with Death. We can maintain this silliness now!

I see it as lucky 7

[10e6Steve]

10-13-2006 would evaluate to 1 + 0 + (-1) + 3 + (-2) + 0 + 0 + 6 which equals lucky 7.

Re:I see it as lucky 7

[Anonymous Coward]

No, it's 10/13/2006, which is lucky 0.00038346499

Wasn't this on South Park The other night?

[SrLnclt]

Cartman: Twelve contains the numbers 1 and 2 just like the toilet yesterday where somebody went #2 instead of #1. Add 2 and 1 with 911 and you get 914. Drop the 4 and its 91. Exactly the score Kyle got on his spelling test 12 days after 9/11!

inverse relation to perverse months

[Anonymous Coward]

There's an old piece of trivia from a Martin Gardener's Scientific American column many years ago. The more Friday 13ths in a year, the less perverse months in that year. A perverse month is one that requires 6 rows (or a folded 5th row) to represent on a calendar. So, a bad year for the superstitious, a good year for the calendar printers.

There's is nothing mystical about the relationship, it's just the way it turns out in the 28 year cycle.

OT: Sig reply

[NotQuiteReal]

...I'm listening to the guy with the lens in a tube rather than the guy with the corpse on a stick

I hope you are right in the long run, but for immediate, practical purposes, the STICK has more WHACKING heft.

Re:OT: Sig reply

[fuzzix]

I hope you are right in the long run, but for immediate, practical purposes, the STICK has more WHACKING heft.

I keep my lart polished and my wrist keen and sharp.

Re:OT: Sig reply

[Reziac]

I dunno. Last tube with a lens in it that I saw would have completely crushed anyone who blundered underneath it. :)

As to the nominal topic... some years ago I was on my way to a SF convention, and the date happened to be Friday the 13th. I stopped at Costco to get a big bag of M&Ms and one other minor item, I forget what. The total turned out to be $13.13 .... Coincidence? ;)

European form?

[miasmic]

The European Form of writing dates? More like the USA's form of writing dates, and then all the other countries in the world's way of writing dates.

Ahh, I remember it well ...

[smoker2]

the time was 1:23:45 on the 6th day of the 7th month of the year '89.

How we celebrated !

Happy days, happy days ....

Of course, we all thought digital watches were a pretty neat idea.

supernatural

[jqstm]

Do all supernatural entities count in base ten?

Don't fall for this...

[Anonymous Coward]

It is bad luck to be superstitious.

13

[djones211]

someone has absolutely nothing better to do.

Freaky Friday

[DigitAl56K]

I'm not one for superstition, but when Friday the 13th comes around and Slashdot manages to actually publish an article on it before Saturday the 14th, well.. what can I say?

Re:10 + 13 + 2006 = 2029...these add up to 13 too!

[Anonymous Coward]

JJ Abrams called, he wants his calculator back.

1+2 = 3, But It's a Shock 2+1 Does Too

[MSTCrow5429]

"whether you write it in the US or the European form"

So you mean those mythical and mostly unknown rugged nomads and cave people of Europe use the same calendar we do? Wow!

All Hands Meeting

[mulhollandj]

I once had an All Hands Meeting on a Friday the 13th. They laid off 20% of the work force.

Re:10 + 13 + 2006 = 2029...these add up to 13 too!

[Anonymous Coward]

Yes, anytime you are numerologizing, adding up digits, you can add up the numbers first, then the digits, and get the same result.

...a physicist at the University of Slashdot...

[Anonymous Coward]

Jan. 13, 1520 = 01/13/1520 = 0+1+1+3+1+5+2+0 = 13

"The phenomenon hasn't happened since this morning at 12:00am, said Anonymous Coward, a physicist at the University of Slashdot, who crunched the numbers using calc.exe to find that the double-whammy last occurred 1 millisecond ago..."

pokermatch

[Anonymous Coward]

Well I won four out of four poker games tonight raking in about 200 euro's. When's thje next fri 13?

I don't believe in Friday 13th

[guruevi]

I believe in Thursday the 12th. It's the day you should stay in bed.

I was late for work
At work a laptop irrepairably failed
A co-worker got fired
More workload added
None of my scripts worked
Power went out in the building
Imaging a computer failed 3 times
Went home late, started snowing heavily on the way home
No dinner ready
Dinner tasted bad
Had to get gas
Had to pick friend up unexpectedly
Got a ticket speeding for gas and friend
Was late picking up friend
Very late for a gathering
Had to see ex-girlfriend
Seems like I was disinvited for a party
Went finallly home, apparently forgot the stove, pan burnt out and house smelling like charcoal
House kept smelling like charcoal, annoying trying to sleep
Dog wouldn't shut up and go to sleep, constantly came pushing to play with his ball
Shut out dog, dog scratching to get back in
During the night into the 13th power went out for the residence
Freak snowstorm

Well, Thursday the 12th was the worst day in months. Nothing really bad happened on the 13th, actually my ex-girlfriend started e-mailing more frequently and I went home early from work.

Re:I don't believe in Friday 13th

[wuie]

My Thursday the 12ths have always been bad as well. I only had my car towed yesterday though, so it doesn't quite compare to the day you had. :/

Re:I don't believe in Friday 13th

[Anonymous Coward]

Boy, what a long cover-story for mentioning the word 'girlfriend'...

January 13 1520 was a Thursday

[ygasuasu]

The Gregorian calendar started in 1582 (http://en.wikipedia.org/wiki/Gregorian_calendar): The last day of the Julian calendar was Thursday 4 October 1582 and this was followed by the first day of the Gregorian calendar, Friday 15 October 1582. So, January 13th, 1520 was a Thursday. However, October 13th, 1520 was a Friday and the sum of the digits were also thirteen.

Re:January 13 1520 was a Thursday

[SnarfQuest]

If you read the Wikipedia article quoted, you will note that not all countries switched to the gregorian calander at the same time. Russia held out until the 1900's. However, none of the dates in the range would meet the ./ criteria.

Good form.

[Somatic]

I'm not one to take the side of the US in the "US vs. World" debates, but in this case, the US form makes more sense. Putting the year first in a date is a waste of reading time because you always know what year it is. Putting it last lets the eye read it more quickly-- you see the month and day, and comment out the rest (except in languages that read right to left, but I'm pretty sure they don't use our char set).

Minor point, maybe. Personally, I have a job that requires me to read 50-100 dates a day, and input about a third of that. So yeah. The US form takes this round. But I'm with you on the metric system, and Dr. Who.

Re:Good form.

[1u3hr]

I'm not one to take the side of the US in the "US vs. World" debates, but in this case, the US form makes more sense. Putting the year first in a date is a waste of reading time because you always know what year it is.

The "rest of the world" is as likely to put DMY as YMD. Either makes sense and is unambiguous. The problem is the US form MDY, which causes endless confusion.

Re:Good form.

[OneSmartFellow]

Putting the year first in a date is a waste of reading time because you always know what year it is.
What about dates that refer to the distant past or the distant future, and so span more than one year.
The real advantage of year/month/date (or day/month/year) is sorting - since this form will sort correctly as text (under most circumstances), where as sorting month/day/year as text doesn't help you much at all. The other advantage of using day/month/year of course is that THE REST OF THE WORLD DOES IT THAT WAY and that's enough of an advantage by itself to warrant the US switching to that style.

Re:Good form.

[TCM]

the US form makes more sense.

No it doesn't. It mixes the significance of the numbers. Your explanation hardly makes any sense because any benefit is outweighed by non-intuitiveness. You say one already knows what year it is. Well, why don't you already know the month, too? According to your "logic", the day should be the first, since it's the item that changes most frequently. Being accustomed to something != making sense.

YYYY-MM-DD is easily sortable for computers and is also the standard set by ISO 8601. This is the only correct and intuitive notation. Some countries use(d) DD.MM.(YY)YY which is at least easy to read for humans and maintains the order of most frequently changing to least frequently changing item. MM/DD/YY is just a mess and I can't count the times I've been confused by it.

All this gets worse when people use YY/MM/DD, DD/MM/YY or YYYY-DD-MM as I've seen recently, although the latter must have been a typo. As if ../../.. wasn't bad enough, they use USA syntax but ISO semantics, WTF?

I don't understand...

[puracc]

...why do people panic on my birthday every few years?

<music>happy birth day dear puracc~~~ happy birthday to you~~~</music>

Re:I don't understand...

[PatTheGreat]

No foo! "Happy Birthday" is copyrighted! You just cost yourself like, a bazillion dollars.

Playing with dates

[suso]

I was just playing around with cal, reading the man page and found this:


$ cal 9 1752
      September 1752
Su Mo Tu We Th Fr Sa
        1 2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30


That's a really weird month. Appearently, the September Massacres happened on September 2nd, 1752. Don't know if there is a relationship there.

Also, I was playing with for loops, numsum, sed and such and came up with this list of years that also had Friday 13th in October and all the numbers added up to 13.

80
125
170
215
332
422
1133
1223
1340
1430
2006

I'm not sure whether this is accurate though with respect to the change from Julian to Gregorian calendars though. 2006 marks the 11th time this happened since the year 1. Interestingly, the 13th occurance of this will be in 2141, which is also the last one that will occur in the 3rd millinium. The 14th one doesn't occur until 3122 and there are only 20 of them total in the first 10,000 years. I guess they are pretty rare. My wife and I have actually found the number 13 to be lucky for us more than unlucky. But they are just numbers.

Re:Playing with dates

[bytesex]

Erm.. aren't they all adding up to eight ?

Re:Playing with dates

[suso]

What is more interesting is this. This file has all the years that have a Friday October 13th in them in which the entire date adds up to 13.
suso@lata ~ $ cat special-years-13
80 1
125 2
170 3
215 4
332 5
422 6
1133 7
1223 8
1340 9
1430 10
2006 11
2051 12
2141 13
3122 14
3302 15
4130 16
4220 17
4400 18
5111 19
8000 20
suso@lata ~ $ cat special-years-13 | interval # This calculates the interval between every two numbers.
45
45
45
117
90
711
90
117
90
576
45
90
981
180
828
90
180
711
2889
Wow! Look at how many 9s are in all those numbers:
45 = 4 + 5 = 9
45 repeat
45 repeat
117 = 1 + 1 + 7 = 9
90 = 9 + 0 = 9
711 = 7 + 1 + 1 = 9
90 repeat
117 repeat
90 repeat
576 = 5 + 7 + 6 = 18 (9 * 2)
45 repeat
90 repeat
981 = 9 + 8 + 1 = 9 + 9
180 = 1 + 8 + 0 = 9
828 = 8 + 2 + 8 = 18 (9 * 2)
90 repeat
180 repeat
711 repeat
2889 = 2 + 8 + 8 + 9 = 18 + 9

If anyone wants to take the time to work this out as an abstract algebra problem, I'd be curious to see how such a pattern emerges.
You know, I get really tired of stupid Slashdot restrictions like this:
"Your comment has too few characters per line (currently 9.1)."
Then I have to add more useless text onto my post just so that it will accept a post that has some numerical analysis related to the article. While I can understand why they do these kinda checks, sometimes they are such a hassle. It still doesn't think I have enough characters per line. So I'm still adding text to this post. I thought it was kinda funny how they say in the article "a physicist at Germany's University of Aachen who crunched the numbers" as if the number crunching to calculate this was worthy of a super computer. I was able to make these calculations using num-utils, a couple of for loops and sed in about 5 minutes. Unfortunately, cal doesn't go past the year 9999. But oh well, at least its a nice accurate calendar. Well, its still telling me that I don't have enough characters per line (19.3 now). Sheesh. Probably now that I've put all this into my post, someone will mark me down as -1, Troll without really reading the comment and understanding what kind of hell I went through to get this posted on Friday the 13th.

Re:Playing with dates

[Anonymous Coward]

The digits in the years do add up to 8. However, the topic was about the digits of the year AND month AND day adding up to 13 and the parent was talking about the occurences of October having a Friday the 13th. So, (8) [for each year] + (1 + 0) [for october] + (1 + 3) [for the 13th] = 8+1+0+1+3 = 13.

Now, I was playing around with the numbers and found that there can be a TRIPLE-whammy!!! This will happen when there is a Friday the 13th in January. The reason is because the 13th day in January is the 13th day of the year! So this year there was a TRIPLE-WHAMMY!!! Anyway, I was also going to point out that it might happen on a Friday the 13th in September, because the 13th day in September is the 256th day of the year, 2+5+6=13. However, (unfortunately) September is the 9th month so we get 9+1+3+yyyy = 13+yyyy. So, unless it's the year 0, this form of a triple-whammy won't happen. :( Oh well, it was a fun thought experiment while it lasted.

Re:Playing with dates

[root_42]

I was just playing around with cal, reading the man page and found this:

$ cal 9 1752
September 1752
Su Mo Tu We Th Fr Sa
1 2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

That's a really weird month. Appearently, the September Massacres happened on September 2nd, 1752. Don't know if there is a relationship there.

From the manpage of cal(1):

The Gregorian Reformation is assumed to have occurred in 1752 on the 3rd of September. By this time, most countries had recognized the reformation (although a few did not recognize it until the early 1900's.) Ten days following that date were eliminated by the reformation, so the calendar for that month is a bit unusual.

Re:Playing with dates

[x2A]

Instead of
"576 = 5 + 7 + 6 = 18 (9 * 2)"

you could have continued to the 9, in which case they all result in 9 :-)

576 = 5 + 7 + 6 = 18, 1 + 8 = 9

Re:Playing with dates

[suso]

Actually, this property of numbers was a bit surprising, it turns out it doesn't have anything to do with the dates at all (of course). From playing around a bit more, I've discovered the following property of the number 9.

Any set of numbers whose digits add up to the same number, have a difference between each other whose digits will add up to a multiple of 9. This seems to work for any number. I haven't been able to find if this property was known or if I discovered something new. Probably its already known. Anyone know the name for it?

This IS a common phenomenon

[figgypower]

The parent is right... the phenomenon has taken place multiple times, way before 476 years.

At the burger joint

[bidule]

I went for food at an A&W burger joint. Their cash register weren't working properly, they had to shout the order to the kitchen. That was unusual.

Walking under ladders

[KayEss]

British psychologist Richard Wiseman may be more attuned to Friday the 13th than anyone. His landmark survey of 4,000 adults in 2003 found that a quarter of them said the number 13 was unlucky, 64 percent crossed their fingers for luck and 49 percent refused to walk under ladders.

Not walking under ladders seems eminently sensible to me. Especially if there's somebody up there holding a pot of paint. Of course if you're the one up the ladder then not having people walking under and into it is also a good idea.

Re:Walking under ladders

[x2A]

yeah, is kinda like 'not walking out in front of cars' huh!

Re:But isn't that really 4?

[iOsiris]

The Chinese associates the number four with death only because the words four and die/death sound so similar with only a minor tone shift. Its quite amusing listening to learners of Chinese repeatedly saying 'die!'

nightmare

[Wiarumas]

As a araskevidekatriaphobic, this is by the far the worst day of my life.

Bah.

[jpardey]

When they add up to 5318008, let me know.

I care about it because...

[fbjon]

It's my birthday, you insensitive clod!

Doh

[TheLink]

It is fun and useful to celebrate weekends, annual events, birthdays etc.

But never forget that this very second hasn't ever happened and will never ever happen again (unless God decides to rerun this very moment of Universe 0.1 ;) ).

And I'm wasting it on Slashdot :p

Let's celebrate...oops

[C4st13v4n14]

I'm so happy I was made aware of this on Saturday the 14th at about 1am.

But it ain't Tuesday the 13th...

[srussia]

which is supposed to be the unlucky day (at least here in Spain, which is in Europe BTW)

Re:But it ain't Tuesday the 13th...

[heinousjay]

What is this 'Europe?'

Clueless mods?

[Teun]

For 'The Believers' this weather on a Friday the 13th. must indeed be scary!

The fact that a Mod could not see this link is scary in itself...

Before 10000...

[Gothmog of A]

there will be the following dates with this property

2011-05-13
2012-04-13
2013-12-13
2032-02-13
2051-01-13
2051-10-13
2101-05-13
2122-02-13
2122-11-13
2141-01-13
2141-10-13
2204-01-13
2210-04-13
2211-12-13
2212-11-13
2300-04-13
2301-12-13
2320-02-13
3000-06-13
3012-03-13
3032-01-13
3040-11-13
3103-02-13
3103-11-13
3122-01-13
3122-10-13
3212-01-13
3220-11-13
3302-01-13
3302-10-13
4001-04-13
4002-12-13
4020-03-13
4040-01-13
4111-02-13
4111-11-13
4130-01-13
4130-10-13
4201-02-13
4201-11-13
4220-10-13
4400-10-13
5001-03-13
5111-01-13
5111-10-13
8000-10-13

Re:Before 10000...

[FhnuZoag]

Yeah. I was going to make this point too - the property of this date isn't really that rare - it's rare and not rare depending on the part of the milennium you are in. For the last 500 years, when the year went from 15xx to 199x, there was obviously little chance of having a total that added to 13. Saying that the fact that it hasn't happened in the last 500 years means that it is 'rare' is just cherry picking.

Wow, on either side of the pond!

[foxtrot]

add up to 13 -- whether you write it in the US or the European form.

But I was sure the commutative property of addition didn't work in Europe!

Oh, you haven't heard?

[Poromenos1]

Yeah, all today's preorders have been canceled. Sorry man :(

The phenomenon hasn't happened in 476 years

[Anonymous Coward]

"The phenomenon hasn't happened in 476 years" BS!!! Here is a little fun:

cal 01 2006

        January 2006
Su Mo Tu We Th Fr Sa
  1 2 3 4 5 6 7
  8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31

It happened in Jan 2006.

Towelie?

[Anonymous Coward]

Towelie?

In other news...

[dcollins]

In other news, the last winning Powerball jackpot numbers had only 1 in 146 million chance of coming up the way they did! So did the time before that. So will the next one. Etc.

The Washington Moonie?

[Geste]

Juha-Matti Laurio writes to point out a Washington Times story

Juha-Matti, being from Finland, may have incorrectly formed the impression that the Washington Times is a newspaper. I can see how he might have missed the fact that the WT (along with UPI) is a propaganda outlet operated by Sun Myung Moon.

Re:The Washington Moonie?

[Detritus]

Have you ever bothered to read the newspaper? It may be owned by a nut, but the newspaper isn't bad.

You know

[Anonymous Coward]

13.1.2006
13.10.2006
13.5.2011
13.4.2012
13.12.2013
13.2.2032
13.1.2051
13.10.2051
13.5.2101
13.2.2122
13.11.2122
13.1.2141
13.10.2141
13.1.2204
13.4.2210
13.12.2211
13.11.2212
13.4.2300
13.12.2301
13.2.2320

From 2000-2500, credits to pllk on mbnet.fi. We've had two such days this year.. did people miss it last time or something?

666 Special

[itsybitsy]

If you go to Panera and order their "Pick Two" (of 1/2 sandwitch, soup or salad) plus a Washington Post paper (35 cents) you'll end up with a total of $6.66. Of course you must pay with six ones, six dimes and six pennies.

Enjoy

Associative Property

[__aawdrj2992]

The digits in the numerical notation for the date add up to 13 whether you write it in the US or the European form.

It's called the associative http://en.wikipedia.org/wiki/Associative_property

No

[p3d0]

Not 13 sq ft. It's a 13-foot plot. The depth isn't specified.

What about Fri, Jan 13, 2006?

[fahrbot-bot]

"The phenomenon hasn't happened in 476 years, said Heinrich Hemme, a physicist at Germany's University of Aachen who crunched the numbers to find that the double-whammy last occurred Jan. 13, 1520."

Ummm... Unless I'm missing something, the guy missed Friday, January 13, 2006. The numbers 01/13/2006 also add up to 13.

Re:10 + 13 + 2006 = 2029...these add up to 13 too!

[Anonymous Coward]

And 1+3=4, hahahahahhaaaaa!!!

no, wait....