Identify and use arithmetic patterns to multiply

This lesson reviews patterns in the nines fact sequence that were introduced in the previous two lessons. Students examine the 9 = 10 - 1 pattern for multiplication using arrays and think about how the tens digit in the product of a nines fact (? 90) is 1 less than the multiplier and that the ones digit in the product is 10 minus the multiplier. (For example, in 9 × 3 = 27, 2 = 3 - 1, and 7 = 10 - 3.) Then they work at stations to apply different strategies for multiplying nines facts.