billroper: (Default)
[personal profile] billroper
I was impressed by Katie the other night. She was in here with me and starting working on her multiplication tables while I was looking something up on the computer. She wrote down a great number of "8 times X" examples, then tore off a corner of the paper and wrote down:

"anything x 5 = half the number. Katie :)"

Yup, you got it, girl. :)

Date: 2015-09-16 09:31 pm (UTC)
mneme: (Default)
From: [personal profile] mneme
Great intuition! Yeah, while I kinda wish they taught the quick math tricks like 5x = 1/2 x * 10, not to mention for i in (3,9) { if(divisible(sum(digits of X),i), then(divisible(x,i) }.

But on the other hand, it was -so- satisfying to figure those out for myself as a kid; not something I'd have an opportunity to figure out for myself, likely, if they'd been included in "math skills". [On the third hand, the more basic skills you learn, the likelier you are to come up with something interesting on your own, so they probably -should- teach more practical math tricks.]

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