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What pattern did you notice in Problem 1(a)? How can this strategy help you check your work with
nines facts?

Respuesta :

Answer:

So for the 9's facts, we can use a 10's fact, and then just subtract one group. For example, for 9×3, first do 10×3 to make 30, and then subtract one group of 3 to make 27. For 9×7, first do 10×7 to make 70, and then subtract one group of 7 to make 63.