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**Estimating Sums and Differences**

Lesson 4-1

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Benchmark Numbers A benchmark is a number that is easy to use when you estimate. When estimating the sums and differences of fractions, we use the benchmarks 0, ½, and 1. (chart on page 171 of book)

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**½ ½ 3 5 + 11 25 + = Change each fraction to 0, ½, or 1.**

Add or subtract. 3 5 + 11 25 + =

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Example 2 7 4 + 9 15 = 1 +

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**Estimating Mixed Numbers**

If you have mixed numbers, then round the fraction part up to 1 or down to 0. If the fraction is greater than ½, then round up to 1. If it is less than ½, then round down to 0.

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Example 15 3 10 1 4 8 10 6 16 =

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Homework Time

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