Monday, August 10, 2009

Multiplying In Your Head

I think all students should know how to use the standard computation algorithms before using calculators; this guy, however, doesn't even need a calculator!

In seconds, Clay multiplies a pair of five-digit numbers and writes down the answer in a single line. There's none of the sloppy rows of zig-zagging numbers that would normally clutter a page. Such is the beauty of his homemade formula -- titled "How to Multiply Any Number by Any Number in Your Head" -- which is registered as TXu001325432 in the U.S. Copyright Office.

This next part is interesting and can have a certain value, but it's not one I'd impose upon students:

Clay's technique may be novel, but there are dozens of tricks for multiplying large numbers without pen or pad, especially in China and Japan, said Moody Chu, math professor at N.C. State University. Chu knows of a competition in East Asia that has schoolchildren racing to spit out the answers to three-digit problems, all figuring done silently and hands-free.

Maybe my standards are too low.


Ellen K said...

There was a news report last year about a man who had learned to multiply everything in his head. There was a trick to it and he taught it to his students. It was amazing. I wish someone had known that when I was in school.

Anonymous said...

Its an interesting party trick, but does it really have any inherent value as a skill? I am not so sure that it does.

Erica said...

Heck yeah it has value. The whole "who uses math in the outside world?" idea is just a happy fantasy invented by high schoolers.

Even in positions you wouldn't consider math-based careers one needs to perform multiplication endlessly. Don't even get me started on when I had to teach a remedial math class to my front office staff so they'd harassing me to do fractions for them....