[i]I'm not fond of math and numbers, but this was cool. If you want to ask, don't ask me, get a math expert haha![/i] [quote][color=brown][b]The 11 Times Trick[/b][/color] We all know the trick when multiplying by ten - add 0 to the end of the number, but did you know there is an equally easy trick for multiplying a two digit number by 11? This is it: Take the original number and imagine a space between the two digits (in this example we will use 52: [b]5_2[/b] Now add the two numbers together and put them in the middle: [b]5_(5+2)_2[/b] That is it - you have the answer: [b]572[/b]. If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first: [b]9_(9+9)_9[/b] [b](9+1)_8_9[/b] [b]10_8_9[/b] [b]1089[/b] - It works every time.[/quote] [quote][color=brown][b]Subtracting from 1,000[/b][/color] To subtract a large number from 1,000 you can use this basic rule: subtract all but the last number from 9, then subtract the last number from 10: [b]1000[/b] [b]-648[/b] [b]step1:[/b] subtract 6 from 9 = 3 [b]step2:[/b] subtract 4 from 9 = 5 [b]step3:[/b] subtract 8 from 10 = 2 answer: [b]352[/b][/quote] [quote][color=brown][b]Quick Square[/b][/color] If you need to square a 2 digit number ending in 5, you can do so very easily with this trick. Mulitply the first digit by itself + 1, and put 25 on the end. That is all! [b]252 = (2x(2+1)) & 25[/b] [b]2 x 3 = 6[/b] [b]625[/b][/quote] [quote][color=brown][b]Multiply by 5[/b][/color] Most people memorize the 5 times tables very easily, but when you get in to larger numbers it gets more complex - or does it? This trick is super easy. Take any number, then divide it by 2 (in other words, halve the number). If the result is whole, add a 0 at the end. If it is not, ignore the remainder and add a 5 at the end. It works everytime: [b]2682 x 5 = (2682 / 2) & 5 or 0[/b] [b]2682 / 2 = 1341[/b] (whole number so add 0) [b]13410[/b] Let’s try another: [b]5887 x 5[/b] [b]2943.5[/b] (fractional number (ignore remainder, add 5) [b]29435[/b][/quote] [quote][color=brown][b]More Tricks[/b][/color] http://listverse.com/science/10-easy-arithmetic-tricks/ [i][b]- Multiply by 9 - Multiply by 4 - Calculate a Tip - Tough Multiplication - Dividing by 5 - Assorted Multiplication Rules[/b][/i][/quote]

Last edited by Padme (2007-09-20 14:18:49)