Section B Section B Checkpoint

Problem 1

Find the value of each difference. Use an algorithm or strategy of your choice.

  1. 288−197288 - 197
  2. 506−388506-388
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Solution
  1. 91. Sample response:
    Subtraction.
  2. 118. Sample response:
    Subtraction.
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Sample Response
  1. 91. Sample response:
    Subtraction.
  2. 118. Sample response:
    Subtraction.

Problem 2

Here is how Elena found the value of 731−498731 - 498.

\begin {align}\\ 498 + \hspace{.45cm}2 &= 500\\ 500+200&=700\\ 700+\hspace{.25cm}30&=730\\ 730+\hspace{.45cm}1&=731\end{align}

200+30+2+1=233200+30+2+1=233

Explain why Elena's strategy accurately finds the value of 731−498731-498.

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Solution

Sample response: Elena finds how much she needs to add to 498 to get 731. This is the same as the difference 731−498731 - 498.

Show Sample Response
Sample Response

Sample response: Elena finds how much she needs to add to 498 to get 731. This is the same as the difference 731−498731 - 498.