Apr 26 2008
Quick multiplication trick
Here’s a quick trick for mentally multiplying two numbers which are greater than or equal to 10 but less than 20.
Let’s use 18 and 19 as an example.
Add the second digit in one of the numbers to the other number.
18 + 9 = 27
Now, add a zero (mulitply by 10)
27 x 10 = 270
Multiply the […]