Estimate Sums and Differences using Benchmark Numbers

Examples, solutions, and videos to help Grade 4 students learn how to estimate sums and differences using benchmark numbers.

Topic F: Addition and Subtraction of Fractions by Decomposition

Common Core Standards: 4.NF.3c, 4.NF.3d, 4.MD.4, 4.MD.2

NYS Common Core Grade 4 Module 5, Lesson 29

Download Worksheet for Common Core Grade 4, Module 5, Lesson 29

Lesson 29 Concept Development
Problem 1: Estimate the sum or difference of two mixed numbers by rounding each fraction.
Problem 2: Round two mixed numbers to the nearest half or whole, and then find the sum.
Problem 3: Estimate the difference of two fractions greater than 1.
Problem 4: Use benchmark numbers or mental math to estimate the sum and difference of two mixed numbers.

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Lesson 29 Problem Set

1. Estimate each sum or difference to the nearest whole or half by rounding. Explain your estimate using words or a number line.
2. Estimate each sum or difference to the nearest whole or half by rounding. Explain your estimate using words or a number line.(Improper fractions)
3. Montoya’s estimate for 8 5/8 - 2 1/6 was 7. Julio’s estimate was 6 1/2. Whose estimate do you think is closer to the actual difference? Explain.
4. Use benchmark numbers or mental math to estimate the sum or difference.
   

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Lesson 29 Homework

1. Estimate each sum or difference to the nearest whole or half by rounding. Explain your estimate using words or a number line.
2. Estimate each sum or difference to the nearest whole or half by rounding. Explain your estimate using words or a number line.
3. Gina’s estimate for 7 5/8 - 2 1/2 was . Dominick’s estimate was 5 1/2. Whose estimate do you think is closer to the actual difference? Explain.
4. Use benchmark numbers or mental math to estimate the sum or difference.
   

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