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Teacher Notes

KS2 Calculation Ma2 - 3a - Number operations and the relationships between them.

This activity will help children know all addition and subtraction facts for all numbers up to and including 20.

Addition and Subtraction Facts up to 20 - 1

Subtraction reverses addition sums (Subtraction is the inverse of addition) - look at this example:

18 + 1 = 19       19 - 1 = 18
Type in the correct answer to these addition sums.
0 + 19 =           10 + 9 =
1 + 18 =           11 + 8 =
2 + 17 =           12 + 7 =
3 + 16 =           13 + 6 =
4 + 15 =           14 + 5 =
5 + 14 =           15 + 4 =
6 + 13 =           16 + 3 =
7 + 12 =           17 + 2 =
8 + 11 =           18 + 1 =
9 + 10 =           19 + 0 =
What do you notice about the pattern of the answers?

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