Math Whiz Breaks Calculation Record

keyshawn632 writes "The Associated Press reports that Gert Mittring, 38, needed only 11.8 seconds to calculate the 13th root of a 100-digit number in his head at a math museum in Giessen, a small town, located in western Germany. It's worth noting though that his feat will not be recognized by The Guinness Book Of World Records because of the difficulty of standardizing such mathematical challenges."

Comments

Devi: another brilliant mathematical mind

[GreenPenInc]

When I was a kid, my dad lent me a book of Shakuntala Devi's book, "Figuring". She was famous some years ago (in the 50s, I believe) for her own computational ability, multiplying two 13-digit numbers in her head in 28 seconds.

The book itself was an interesting read, and at the time I just ate it up. It has a lot of tricks regarding number theory, mathematical riddles, calendar tricks, and calculation of pi, for example. It teaches how to figure the day of the week for any Gregorian date of any time in a few seconds, a trick which I still remember and use today!

As for the Pi, it contained a few poems and sayings whose letter counts signified the individual digits. I started trying to memorize pi, with my sights set firmly on the world record (as I am not without my own mathematical and mnemonic prowess). However, around grade 9, I decided to abandon my quest in order to get a life. I had memorized 1350 digits at that point.

One such quote held little significance for me at the time, but has since become hilarious. "How I want a drink, alcoholic of course, after the heavy chapters involving quantum mechanics!" Needless to say, my quantum prof found it quite funny. :)

I so call bullshit

[tomstdenis]

Unless there is some really trivial algorithm for finding 13th roots I totally call bullshit. If it takes him four seconds to memorize a 22 digit number how can he manipulate and find a 13th root for a 100 digit number in just over twice that amount of time?

There has to be a trick to it aside from "thinking really fast"

Tom

To how many significant figures?

[jwise]

And how much about the problem did he know in advance? Did he know it would be a 13th root of a 100-digit number? Did he know that the number would be a perfect 13th power of an integer? I find it impossible to believe he calculated a 13th root of a 100-digit number in 11.8 seconds without knowing any of these things. Knowing all of them makes the problem a lot easier.

The 13th root of a 100-digit number will always have 7 digits. If you memorize the first few digits of the 13th powers of numbers between 49 and 58 and you are given a 100-digit number, then you immediately know the first 2 digits of the 13th root. Memorize the initial digits of 13th power of numbers between 491 and 588 and you immediately know the first 3 digits. By memorizing the terminal digits of 13th powers of numbers less than 100, you could similarly immediately get the last 3 digits. That leaves 1 digit to compute, which is a slightly less impressive-sounding feat for 11.8 seconds. It's not a trivial calculation, though, and not at all shabby for 11.8 seconds.

Jonathan

Roomie in College

[AlexTheBeast]

I roomed with a guy in college who would calculate a 10 digit by 10 digit multiplication in his head throughout the day on weekends. He would be grilling or watching TV and you would see him get him and write down 1 digit of his answer.

In grade school he had memorized 52 decks of shuffled cards in some insane short period of time. The teacher would ask him what the 12th card of the 17 deck was... and he would start listing them forward and backward from there.

We often went to the casinos with him. He would card count and we just would bet whatever he would bet. We would all make a $100 or so and leave. He was always afraid of getting caught.

Some government agency approached him for running sets of numbers from point a to point b. They liked the fact that he could just put all those digits in his head without a papertrail.

Last I heard of him, he was avoiding math as much as possible... he enrolled in some DO program in a medical school somewhere. Numbers came too easy for this guy... and he knew he would go crazy if he went into a math field.

So now he's a doc somewhere. Probably calculating 10 by 10 digit numbers in his head as he examines you...

Re:High pi

[Nyh]

I read somewhere that you only need about 50 digits of pi to describe a circle the size of the observable universe to within the diameter of a proton, let alone a chocolate donut.

Well, let us see:
radius universe: about 15e9 lightyears
radius proton: 1.2e-15 m

circle with the size of the universe divided by diameter proton:
2*pi*15e9*365*24*3600*300000000/(2*1.2e-1 5)=3.7e41 .
So 42 digits of pi will do.

42? Where did I see this number before?

Nyh