The 11 times trick!

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we all know the trick when multiplying by ten - add 0 to the end of the number, but did you know that there is 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 gonna use 72) 7_2 Now add the two numbers together and put them in the middle: 7_(7+2)_2 That is it - you have the answer:792 If the numbers in the middle add up to a 2 digit number , just insert the second number and 1 to the first: 9_(9+9)_0 10_8_9 It works every time! Enjoy