Multiplying larger numbers by 11

Th ere is a very simple way to multiply any number by 11. Let’s take the example of 123 × 11.

We would write the problem like this:
0123 × 11

We write a zero in front of the number we are multiplying. You will see why in a moment. Beginning with the units digit, add each digit to the digit on its right. In this case, add 3 to the digit on its right.

There is no digit on its right, so add nothing:
3 + 0 = 3

Write 3 as the last digit of your answer. Your calculation should look like this:
0123 / 3 × 11

Now go to the 2. Three is the digit on the right of the 2:
2 + 3 = 5

Write 5 as the next digit of your answer. Your calculation should now look like this:
0123 / 53 × 11

Continue the same way:
1 + 2 = 3
0 + 1 = 1

Here is the fi nished calculation:
0123 / 1353 × 11