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Mathematics · Grades 1–2

Subtraction within twenty

Check subtraction by adding the result back to the amount removed.

Make a worksheet

The key idea

Check subtraction by adding the result back to the amount removed.

a − b = difference

Worked examples

16 − 9 = ?

7 + 9 = 16

7

17 − 12 = ?

5 + 12 = 17

5

Try it yourself

  1. 18 − 5 = ?

  2. 18 − 18 = ?

Check your understanding

Answers and marking notes
  1. 13

    13 + 5 = 18

  2. 0

    0 + 18 = 18

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.