11's Multiplication tricks

There are two rules when multiplying by 11 (eleven).

The first 11 Times Rule:
This is for the numbers 1-9

When multiplying any single digit number by 11 you just write that number twice.

Multiply 11 by 3 to get 33, multiply 11 by 4 to get 44. Each number to 10 is just duplicated.

The second 11 Times Rule:
This is for any two digit number

You are going to take the two digits of your number add them together, and put the sum in between the two digits you started with.  
For example: if you take 11 x 18. Jot down 1 and 8 with a space between it. 1  8.
The sum of 1+8=9, do put the 9 in between the 1 and 8.
so you get 198. 


12 x 11            1    2     1+2=3            132       12 x 11=132
15 x 11            1    5     1+5=6            165       15 x 11=16511's

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