Multiplication tricks

Here are a couple of multiplication tricks that are pretty cool:

Multiply by 5
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:

• 2682 x 5 = (2682 / 2) & 5 or 0


• 2682 / 2 = 1341 (whole number so add 0)


• 13410

Let’s try another:

• 5887 x 5


• 2943.5 (fractional number (ignore remainder, add 5)


• 29435

Multiply by 11
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:

• 5_2


• Now add the two numbers together and put them in the middle:


• 5_(5+2)_2


• That is it - you have the answer: 572.

If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first:

• 9_(9+9)_9


• (9+1)_8_9


• 10_8_9


• 1089 - It works every time.

More math tricks

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