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- ADDING AND SUBTRACTING DOUBLES
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Adding and Subtracting Doubles
Remember the related subtraction facts for doubles facts.
1 + 1 = 2 2 – 1 = 1 |
6 + 6 = 12 12 – 6 = 6 |
2 + 2 = 4 4 – 2 = 2 |
7 + 7 = 14 14 – 7 = 7 |
3 + 3 = 6 6 – 3 = 3 |
8 + 8 = 16 16 – 8 = 8 |
4 + 4 = 8 8 – 4 = 4 |
9 + 9 = 18 18 – 9 = 9 |
5 + 5 = 10 10 – 5 = 5 |
10 + 10 = 20 20 – 10 = 10 |
Let's find difference of 18 and 9.
18 – 9 = ?
Consider the doubles fact:
9 + 9 = 18
Its related subtraction fact is:
18 – 9 = 9
So, the difference of 18 and 9 is 9.