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3.28.2006

Fun Math Finding

For some reason, as Alison was reading TIME in bed last night, I thought about multiplication. I multiplied 10 x 10 and got 100. Then I multiplied 9 x 11 and got 99.

Hmmm...does that work for every number?
3 * 3 = 9; 2 * 4 = 8.
38 * 38 = 1444; 37 * 39 = 1443.
0 * 0 = 0; -1 * 1 = -1.
-1 * -1 = 1; -2 * 0 = 0.

Sweet! (Well, I think so)

This means that:
x*x = ( (x+1)*(x-1) ) + 1

In other words: If you take a number and multiply it by itself, it will always be one more than the number minus one times the number plus 1.

8 comments:

  1. Ouch...my brain hurts! Stop it!

    I thought you were supposed to count sheep in bed not think about things like x*x = ( (x+1)*(x-1) ) + 1.

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  2. Wow... this is why I had to take every math class twice in High School. Thank god it was not the same way in college.

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  3. a fellow math nerd!!!!!
    finally.

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  4. You are a nerd. And I'm pretty sure that's an established math formula. Ask Kim, she's a math nerd, too.

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  5. Annie Geist10:53 PM

    I got mom's genes. I would not have figured that out even ever. Way to go mathmatic Geist!

    ReplyDelete