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estimating the point


Miriam says that she uses estimating to figure out where the decimal point goes when she multiplies decimals. For example, given the problem 1.2 x .98, she says that a reasonable estimate is 1.2 x 1 =1.2. In fact, she even thinks that 1 x 1 is a good enough estimate to help her figure out where the decimal point goes. Then, she multiplies 12 x 98 to get 1,176. She says that this lets her know that the actual answer is 1.176.

Does Miriam’s estimation approach work for all decimals?

(Source: Adapted from Bits and Pieces 3 - Connected Mathematics, 2006)

   

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