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using doubles
A strategy for adding and subtracting that uses a doubles fact you know. For example, use 7 + 7 = 14 to find that 7 + 8 is one more or 15.
using ten
A strategy for adding or subtracting that uses the number 10. For example, if you know 3 + 7 = 10, then 4 + 7 is one more or 11.
