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Difference: counting on

You learn an easy way to subtract when the two numbers are close together: count on.

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How to work it out

  1. Check if the two numbers are close.
  2. Start at the smaller number and count on to the nearest round number, then to the target.
  3. Add the jumps.

502 − 498

  1. Count on from 498 to 500: that is 2.
  2. Count on from 500 to 502: that is 2.
  3. Add the steps: 2 + 2 = 4.
More examples

1005 − 998

  1. Count on from 998 to 1000: that is 2.
  2. Count on from 1000 to 1005: that is 5.
  3. Add the steps: 2 + 5 = 7.

405 − 396

  1. Count on from 396 to 400: that is 4.
  2. Count on from 400 to 405: that is 5.
  3. Add the steps: 4 + 5 = 9.