Yup! That's a cool *trick*! We learned that last year when my son started participating in math competitions. If you have any more cool things like that, please pass them along. We're all math freaks in my house, lol.
Try this: Take the first 3 odd numbers: 1 3 5
Double them: 1 1 3 3 5 5
Draw a line: 1 1 3 | 3 5 5
Divide: 355/113...."almost" Pi!
It is the closest rational approximation to pi with both numerator and denominator less than 1,000. It is so accurate you could use it for "pi" for the rest of your life and never have an appreciable error. In fact, I sometimes put it in my computer programs--to perplex anyone examining the code in the future!
I got more.
--Boris