Here are a couple of multiplication tricks that are pretty cool: Multiply by 5 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: Let’s try another:
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.
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.
1 comment:
it's too early for math... besides that's what my calculater's for
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