What’s 85^{2}? Why, that’s simple! 7,225! How do I know that? Well, thanks to the Vedics (who predate Christ), we have mathematical shortcuts all rolled up in what’s called Vedic Maths.

This particular shortcut tells us that the square of any number ending in 5, ends in 25 and is precede by the number(s) before the 5 (*x*) multiplied by that number plus one (*x* + 1). So in this case, 8 * 9 = 72, then tack on 25 at the end and you get 7,225. Wow!

Via Wired News.

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Did you know of this trick to multiply numbers by 11? Take the number, for example: 15. Separate the ones from the rest of the number (1_5). Add the two numbers and put the result in the tens place (1 + 5 = 6, put it in the tens: 165), carrying over to the hundreds if needs be. 173 x 11 = ?. Step 1: 17_3, step 2: 17 + 3 = 20, step 3: 1903 (add the 2 to the hundreds). Voila! Cool, eh?