Unit 3 – Addition and subtraction
1 Addition and subtraction are inverse operations so they ‘undo’ each other. Look at this number line.
+5
9 10
8
11 12 13 14 15
–5
2 We can use the inverse to help solve missing number problems. Bar models are helpful too. + 10 = 25 − 30 = 20
?
10
30
20
25
?
3 We can use the inverse to check our calculations by ‘undoing’ each one.
38 + 20 = 58
45 = 12 = 34
35
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04/05/2022 15:49
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