My mad math skillz

For all impractical purposes, I stopped doing math at age 18. I say "impractical" because there are, of course, still a few very basic and practical uses for math in my life. These include:

  1. Calculating tips
  2. Doubling or halving a recipe
  3. Making sure my grading percentages (tests = 40%, homework = 20%, etc) add up to 100
  4. That's about all I can think of right now.
On Friday, Eric and his sister and I went to Golden Gate Park and spent a lovely afternoon dozing on the grass in the sun. At some point when I was a bit more conscious than previously, I started idly thinking about math. More specifically I started trying to figure out an easy way to figure out the sequence of perfect squares in my head (double digit multiplication, say 17 x 24, has never been easy for me to do without a pencil and paper). So, for instance, how do I get from 15 x 15 (which I knew was 225) to 16 x 16 (which I couldn't recall off the top of my head)? And, in my sleepy state, I worked out that I could get from 15 x 15 to 15 x 16 by adding 15, and then get from 15 x 16 to 16 x 16 by adding 16. Voila, 225 + 15 = 240 and 240 + 16 = 256. So then I tried this with several more numbers to make sure it worked every time. Yep: getting from 3 squared to 4 squared: 9 + 3 = 12 and 12 + 4 = 16. Excellent. My brain was getting more awake every second and feeling pretty pleased with itself. It was time to really challenge myself and work out - still in my head! - the formula to express this nifty trick I had hit on. (Those of you who are actually still doing any higher math on a regular basis are probably already laughing at me.) Hmm, algebra... well, the first number would be n and the second would be n + 1....

And that was when I realized that I had spent the last half hour laboriously working out in my head, by arithmetical trial and error, that (n + 1) squared = n squared + 2n + 1.

Which I could have told you without a moment's thought when I was twelve.

Comments

Erin (moviemuse) said…
Yes, we are laughing at you. But we love you anyway! :-)
March 23, 2008 at 6:16 PM
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