Students learn to estimate a sum or difference by first rounding each numeral to the place specified in the problem. For example, to estimate 4,909 + 3,217 by rounding each number to the nearest thousand, first round 4,909 up to 5,000, and round 3,21...7 down to 3,000, then add 5,000 + 3,000 to get 8,000. Teacher stands at white board to model problems and explain her work. (1:49)
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July 13, 2009 at 07:00 PM
