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Course 1 4-9 Estimating Fraction Sums and Differences Learn to estimate sums and differences of fractions and mixed numbers.

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Presentation on theme: "Course 1 4-9 Estimating Fraction Sums and Differences Learn to estimate sums and differences of fractions and mixed numbers."— Presentation transcript:

1 Course Estimating Fraction Sums and Differences Learn to estimate sums and differences of fractions and mixed numbers.

2 Course Estimating Fraction Sums and Differences You can estimate fractions by rounding to 0,, or __ The fraction is halfway between and 1, but we usually round up. So the fraction rounds to __

3 Course Estimating Fraction Sums and Differences closer to 0 Each numerator is much less than half the denominator, so the fractions are close to 0. closer to 1 Each numerator is about the same as the denominator, so the fractions are close to __ __ 2 15 __ __ __ __ 9 20 __ 1 2 You can round fractions by comparing the numerator and denominator. closer to Each numerator is about half the denominator, so the fractions are close to. 1 2 __

4 Course Estimating Fraction Sums and Differences Additional Example 1A: Estimating Fractions Estimate each sum or difference by rounding to 0,, or __ = __ is about __ Think: rounds to 1 and rounds to. 6 7 __

5 Course Estimating Fraction Sums and Differences Additional Example 1B: Estimating Fractions Estimate each sum or difference by rounding to 0,, or 1. – 1 2 __ 9 10 __ 7 8 – 9 10 __ – 1 = __ 7 8 – is about 0. Think: rounds to 1 and rounds to __ 7 8

6 Course Estimating Fraction Sums and Differences Check It Out: Example 1A Estimate each sum or difference by rounding to 0,, or __ = __ is about __ Think: rounds to 1 and rounds to. 5 6 __

7 Course Estimating Fraction Sums and Differences Check It Out: Example 1B Estimate each sum or difference by rounding to 0,, or 1. – 1 2 __ __ 2 11 __ 1 – 0 = __ 2 11 __ – is about 1. Think: rounds to 1 and rounds to __ 2 11 __ – 2 11 __ __

8 Course Estimating Fraction Sums and Differences You can also estimate by rounding mixed numbers. You compare each mixed number to the two nearest whole numbers and the nearest. Does 10 round to 10, 10, or 11? 1 2 __ 3 10 __ __ 2 10 __ 1 10 __ 4 10 __ 7 10 __ 9 10 __ 8 10 __ __ 1 2 The mixed number 10 rounds to __ 1 2

9 Course Estimating Fraction Sums and Differences Additional Example 2A: Sports Application The table shows the distances Tosha walked. About how far did Tosha walk on Tuesday and Thursday? 1 10 __ = 10 She walked about 10 miles on Tuesday and Thursday.

10 Course Estimating Fraction Sums and Differences Additional Example 2B: Sports Application The table shows the distances Tosha walked. About how much farther did Tosha walk on Sunday than Thursday? 9 10 __ – 4 9 – 5 = 4 She walked about 4 miles farther on Sunday than on Thursday.

11 Course Estimating Fraction Sums and Differences Additional Example 2C: Sports Application The table shows the distances Tosha walked. Estimate the total distance Tosha walked on Thursday, Saturday, and Sunday. 1 2 __ She walked about 20 miles on Thursday, Saturday, and Sunday __ = __

12 Course Estimating Fraction Sums and Differences Check It Out: Example 2A The table shows the distances Jerry roller skated. About how far did Jerry skate on Tuesday and Sunday? 1 5 __ = 6 He roller skated about 6 miles on Tuesday and Sunday. Jerry’s Roller Skating Distances Distance (mi) __ Day Tuesday Thursday Saturday Sunday

13 Course Estimating Fraction Sums and Differences Check It Out: Example 2B The table shows the distances Jerry roller skated. About how much farther did Jerry skate on Saturday than Tuesday? 1 7 __ – 3 8 – 3 = 5 He roller skated about 5 miles farther on Saturday than Thursday. Jerry’s Roller Skating Distances Distance (mi) __ Day Tuesday Thursday Saturday Sunday

14 Course Estimating Fraction Sums and Differences Check It Out: Example 2C The table shows the distances Jerry roller skated. Estimate the total distance Tosha walked on Tuesday, Thursday, and Sunday. 1 2 __ He roller skated about 12 miles on Tuesday, Thursday, and Sunday. 1 5 __ __ = __ Jerry’s Roller Skating Distances Distance (mi) __ Day Tuesday Thursday Saturday Sunday

15 Course Estimating Fraction Sums and Differences Lesson Quiz: Part I Estimate each sum or difference by rounding to 0,, or 1.

16 Course Estimating Fraction Sums and Differences Lesson Quiz: Part II 5. The conservation club picked up trash along the road for three weeks. The table shows the number of pounds of trash they collected. About how many pounds did they collect in weeks 2 and 3? about 37 pounds


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