ffirs.indd

Multiplication by 11 73
Th e next steps are:
4 + 7 = 11
Write 1 and carry 1. Add the next digits:
0 + 4 + 1 (carried) = 5
Write the 5, and the calculation is complete. Here is the fi nished
calculation:
0 471 × 11
51181
Th at was easy. Th e highest digit we can carry using this method
is 1. Using the standard method to multiply by 11, you can carry
any number up to 9. Th is method is easy and fun.
A simple check
Here is a simple check for multiplication by 11 problems. Th e
problem isn’t completed until we have checked it.
Let’s check our fi rst problem:
0123 × 11
1353
Write an X under every second digit of the answer, beginning from
the right-hand end of the number. Th e calculation will now look
like this:
0123 × 11
1353
X X
Add the digits with the X under them:
1 + 5 = 6
Add the digits without the X:
3 + 3 = 6