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Old 08-26-2016, 02:13 PM
Cartoonacy Cartoonacy is offline
Join Date: Dec 2003
Location: Long Island, NY
Posts: 1,520
Originally Posted by aceplace57 View Post
I can see this trick going horribly wrong. You're 39! No I'm not! Then it becomes obvious the mental arithmetic slipped a gear.
Yeah. I remember when I was in 5th grade, trying a similar trick on my cousin, who is two years older:

"Think of a number. Double it. Add 10. Divide by 2. Subtract the number you first thought of. Your answer is 5."

He laughed hysterically, making fun of me because the trick didn't work. He had just learned about negative numbers in school, so he started with -1. He said that I wasn't so smart, because my trick doesn't work with negatives.

Two years later, I learned about negative numbers myself, and discovered that the trick works fine with them. I guess he didn't understand negatives as well as he thought. (I never did bring it up again, though.)