From a math article...
*** Everyone knows you can count on your fingers. Did you realize you can use them for multiplication? A simple way to do the "9" multiplication table is to place both hands in front of you with fingers and thumbs extended. To multiply 9 by a number, fold down that number finger, counting from the left.
Examples: To multiply 9 by 5, fold down the fifth finger from the left. Count fingers on either side of the "fold" to get the answer. In this case, the answer is 45.
To multiply 9 times 6, fold down the sixth finger, giving an answer of 54. ***
I was going to put a picture of two hands here but couldn't find any semi normal looking pictures of hands. Let alone with one finger bent on one hand.
Anyway, here's a link to the article that has 10 math tricks.
Be prepared to have your mind blown. But have pencil and paper handy.
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8 comments:
Nine is a magic number. While washing up one night I realised that if you add together the digits from any multiple of nine the answer is nine - eg 2 x 9 +18. 1 + 8 + 9.
My family (except me) loves maths. I do not.
I've fascinated lots of children with that nine-multiples finger trick.
Ugh, math.
Ahh...
Our old friend from It's a Numeric Life would be pleased by this post.
Sue - Some math tricks can be fun. As long as you don't have to think too hard.
Bill - I'd never seen that particular one before.
Deb - Do you like math? German answer - Nine!
John - I'm getting old and forgetful. I didn't even think about her.
Cool!
Well, multiplying by nine is fairly easy anyway. Just remember, the more you multiply a number by nine, the more you subtract by one. In other words, 9,18,27,36,45,54,63,72,81,90. Those are the answers. As they say on Jeopardy, here are the questions: 9x1,9x2,9x3,9x4,9x5,9x6,9x7,9x8,9x9,9x10. See the pattern? I aced nines in school. 8,7,6,4--well those multipliers were a little harder. No pattern that I can make out.
But one shouldn't fret. Marilyn vos Savant, who once had the highest score on an IQ test (impossible these days, as the results are capped), pointed out that knowing your math tables is merely a sign of memory, and not necessarily intelligence.
Kathy - 9? 9 degrees is COLD!
Kirk - I went to the same grade school in St. Louis as Marilyn Vos Savant at the same time. Of course, she was in the gifted class and I was not.
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