Times table tricks › The 11s · En español

How to multiply by 11 in your head

For 1 to 9, write the digit twice. For bigger numbers, split the digits and put their sum in the middle.

11 × 7: write 7 twice, 77.
11 × 12: split 1 and 2, put 1 + 2 = 3 in the middle, 132.

Examples

11 × 7: write 7 twice: 77
11 × 12: 1, 1 + 2, 2 → 132

Why it works

11 × n is 10 × n plus n. For a two-digit number, adding those two lines up puts the sum of the digits in the middle.

Multiplying any two-digit number by 11

Split the digits and put their sum in the middle: 11 × 72 is 7, 7 + 2, 2, so 792. If the sum is 10 or more, carry the 1: 11 × 57 is 5, 12, 7, which becomes 627.

Try it: 10 questions

Turn on JavaScript to take the quiz.

The 11 times table

11 × 1 = 11
11 × 2 = 22
11 × 3 = 33
11 × 4 = 44
11 × 5 = 55
11 × 6 = 66
11 × 7 = 77
11 × 8 = 88
11 × 9 = 99
11 × 10 = 110
11 × 11 = 121
11 × 12 = 132

Printable sheet (PDF) The trick, the full table and 20 practice problems with answers, on one page.

Flash cards (PDF)

Common questions

Does the 11 trick work for 11 × 10?

Yes: split 1 and 0, put 1 + 0 = 1 in the middle, 110.

What if the digits add up to more than 9?

Keep the ones digit in the middle and add 1 to the first digit. 11 × 48: 4 + 8 = 12, so 4 + 1, 2, 8 = 528.

More tricks: 2 · 3 · 4 · 5 · 6 · 7 · 8 · 9 · 10 · 12. Or take the 1-minute multiplication test.