Some people are such brainiacs.
The 11 Times Trick
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:
Now that is a great trick! We are counting down the days until the wedding (64), and I wish you were closer so that we could plan a beautiful cake or two :)
Post a Comment