Multiplying a two-digit number by 11 looks hard. It takes about two seconds once you know the trick.

🪄 The trick: Split the two digits apart, then put their sum in the middle.

Example 1: 43 × 11

Split 4 and 3:  4 _ 3

Middle: 4 + 3 = 7

43 × 11 = 473

Example 2: 78 × 11 (the sum is bigger than 9)

Split 7 and 8:  7 _ 8

Middle: 7 + 8 = 15, so write 5 and carry the 1 to the left

7 + 1 = 8

78 × 11 = 858

Why it works

43 × 11 = 43 × 10 + 43 = 430 + 43. The tens digit and the ones digit get added together in the middle column.

Your turn

  1. 52 × 11
    Show answer

    572

  2. 36 × 11
    Show answer

    396

  3. 89 × 11
    Show answer

    8 + 9 = 17, carry the 1: 979

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