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Addition within twenty

You learn additions to twenty where you leave the ten alone and only work with the ones.

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How to work it out

  1. Keep the ten.
  2. Add the ones together.
  3. Put the ten back in front.

13 + 5

  1. Leave the 10 in 13 alone.
  2. Add the ones: 3 + 5 = 8.
  3. Put the 10 back: 10 + 8 = 18.
More examples

12 + 6

  1. Leave the 10 in 12 alone.
  2. Add the ones: 2 + 6 = 8.
  3. Put the 10 back: 10 + 8 = 18.

4 + 11

  1. Leave the 10 in 11 alone.
  2. Add the ones: 4 + 1 = 5.
  3. Put the 10 back: 10 + 5 = 15.