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Key Idea
You can use place
value to add and
subtract whole
numbers. |
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Adding and Subtracting
Whole Numbers |
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How do you add and subtract whole numbers? |
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Find the total area of Lake Michigan
and Lake Ontario. |
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| Estimate: 70,000 + 30,000 = 100,000 |
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| Write
the numbers, lining up places. Add the
ones and then the tens. |
Continue
adding hundreds, thousands, and ten
thousands. Regroup as needed. |
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| The total area is 102,750 square miles. The answer is reasonable because it is close to the estimate. |
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| You can use regrouping to subtract with zeros. |
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Find
4,006 – 2,748. |
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| Subtract the ones. Think of 4,000 as 400 tens. Regroup. |
Subtract tens, hundreds, and thousands. |
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The answer
checks. |
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| Talk
About It |
| 1. | Explain
the regrouping in
Example B, Step 1. |
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