Addition and Subtraction Facts up to 20 - 1Subtraction reverses addition sums (Subtraction is the inverse of addition) - look at this example:
18 + 1 = 19 19 - 1 = 18Type 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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