Slashdot Mirror

← Back to Stories (view on slashdot.org)

Improving Your Mental Math Skills?

Posted by Cliff on from the outperforming-an-abacus dept.

Infrared-Archer asks: "I want to learn how to do most math calculations in my head. That way I won't have to reach for the calculator for problems I should be able to do mentally. Of course there are various websites (beat the calculator) that show many tricks, but I am looking for a comprehensive solution (books, websites) that shows how to solve of wide range of math problems mentally. Any suggestions?"

5 of 136 comments (clear)

  1. No substitute for hard work by Anonymous Coward · · Score: 4, Insightful

    All the tricks are fine, but there is no way around it, you have to practice and keep your skills up. Start adding things up when shopping, calculate tips and sales taxes, etc. When ever you rach for the calculator, see if you can't do it in your head first, at least for a quick estimate.

  2. Best way by Arngautr · · Score: 5, Insightful

    The best way is to simply limit your calculator usage. I like to show off with the folks I tutor by doing their calculations in my head before they can type them into calculators. A strong basis in algebra can help you beak apart calculations into managable chunks, the trick is remembering how to put those chuncks back together. For instance (contrived example so not great but...): 95*23=100*25-100*2-5*23=2500-200-115=2185

    1. Re:Best way by jonjohnson · · Score: 5, Insightful

      And, my favorite trick is to multiply any number by 5, divide it by two, move the decimal place over (multiply by 10). It makes it much easer to grok that in my head, at least. So, 5*1024 is the same as 1024/2 * 10 = 512 * 10 = 5120.

      Work backwards for dividing by 5.

  3. blind leading the blind by MatrixBandit · · Score: 4, Insightful

    Awhile ago I realized that since highschool my own math skills had deteriorated beyond belief. The breaking point was when I was going to buy a 21" monitor and I wanted to figure out what the height and width of the screen would be so I could actually get a feel for what it was I was paying $400 for. It took me about 4 hours of racking my brain trying to remember old algerbra rules to transform the pythagorean theorem to use the diagonal (20" viewable) and a generic aspect ratio 1.333 to derive the height / width.

    My point is that if you want to get quicker with your mental math skills or keep your current pace, you have to keep using it or else it will atrophy like everything else. Translation: college math courses or at home math excercises, but either way don't expect to be able to ever be "done" with it.

    Good luck with that by the way, you're a better man than I.

  4. Just do it! by Captain+Kirk · · Score: 4, Insightful

    Research proves there is no trick or secret. People who rely on calculators are poor at mental math because of lack of practice. While some people do have innate skills in maths, everyone has the ability to train the brain to to basic math. Take a look at this study
    Memory, mental arithmetic and mathematics

    --
    1000s Warcraft Gold while you sleep