From any addition fact such as
35 + 23 = 58
we can work out two subtraction facts.
Here we get
58 - 35 = 23
and
58 - 23 = 35
This is handy because we can use additions to check subtractions.
Example 1
Anna says that
33 - 15 = 18
Use addition to check if she is right or wrong.
Answer
18 + 15 = 33
So Anna is right.
Example 2
Ben says that
54 - 15 = 31
Use addition to check if he is right or wrong.
31 + 15 = 46 not 54
So Ben is wrong.
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