Multiply up to 20 x 20 in your Head

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  1. Picture the two numbers in your head, the larger above the smaller. For example, let’s use 16×18. Imagine 18 above 16 in your head.
  2. Kill the 1 on the bottom number (the 1 on the 16). If you are following this example, you will now have 18 above 6.
  3. Add the two numbers. You should now have 24. Put a zero on the end (this multiplies by 10) to make up for the 1 that was taken off. The result is 240.
  4. Multiply the two numbers in the Ones column on the original two numbers. For example, 6 x 8 = 48.
  5. Add the two numbers you have now, 48 and 240. You should get 288.

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