Inverse operations
Inverse operations helps children practise using the connection between addition and subtraction to write all four facts from one number trio — for example 28, 9, 37. Read the short guide and look through the examples before choosing online practice or a printable worksheet.
How to solve this
- Every addition has two related subtraction facts, and every subtraction has a related addition fact.
- Write all related facts as a family: for 36 + 48 = 84, also write 84 − 48 = 36 and 84 − 36 = 48.
- Check that all equations in the family use the same three numbers and that every one is correct.
Examples
30 + 40 = 70
70 - 40 = 30
28 + 9 = 37
37 - 9 = 28