In this video, I explain how to perform two-digit operations quickly using mental strategies. We'll cover **addition**, ...

19 is only 1 away from 20, so you prefer to start by multiplying 20 times 5, which equals 100. Then we need to take away a squadron of 5, because there are actually only 19 squadrons, not 20. 100 take ...

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understand that the area of a rectangle is the result of a multiplication partition (break apart) a number using your understanding of place value recall times-tables up to 9 x 9 and multiply by ...