Estimating Fraction Sums 4 9 and Differences Learn

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

Estimating Fraction Sums 4 -9 and Differences 1 __ You can estimate fractions by rounding to 0, 2 , or 1. 1 __ 2 0 1 __ 8 1 __ 4 3 __ 8 5 __ 8 3 __ 4 • 1 7 __ 8 3 1 The fraction __ is halfway between __ and 1, but we 4 2 3 usually round up. So the fraction __ rounds to 1. 4 Course 1

Estimating Fraction Sums 4 -9 and Differences You can round fractions by comparing the numerator and denominator. 1 __ 2 0 • closer to 0 1 __ 5 2 __ 11 2 __ 15 Each numerator is much less than half the denominator, so the fractions are close to 0. Course 1 1 __ closer to 2 5 __ 9 4 __ __ 11 7 20 Each numerator is about half the denominator, so the fractions are 1. close to __ 2 1 • closer to 1 9 __ 10 16 __ 19 6 __ 7 Each numerator is about the same as the denominator, so the fractions are close to 1.

Estimating Fraction Sums 4 -9 and Differences Additional Example 1 A: Estimating Fractions 1 2 Estimate each sum or difference by rounding to 0, __, or 1. 6 3 __ __ + 7 8 6 __ + 7 3 __ 8 6 3 1 Think: __ rounds to 1 and __ rounds to __. 7 8 2 1 1 __ __ 1 + =1 2 2 1 6 3 __ __ __ + is about 1. 2 7 8 Course 1

Estimating Fraction Sums 4 -9 and Differences Additional Example 1 B: Estimating Fractions 1 2 Estimate each sum or difference by rounding to 0, __ , or 1. 9 __ – 10 7 __ 8 7 9 __ __ – 8 10 9 7 Think: __ rounds to 1 and __ rounds to 1. 10 8 1 – 1 =0 9 7 __ __ – 10 8 Course 1 is about 0.

Estimating Fraction Sums 4 -9 and Differences Check It Out: Example 1 A 1 2 Estimate each sum or difference by rounding to 0, __, or 1. 5 3 __ __ + 6 7 5 3 1 Think: __ rounds to 1 and __ rounds to __. 6 7 2 1 1 __ __ 1 + =1 2 2 5 3 1 __ __ __ + is about 1. 6 7 2 Course 1

Estimating Fraction Sums 4 -9 and Differences Check It Out: Example 1 B 1 Estimate each sum or difference by rounding to 0, __, or 1. 2 13 __ – 19 2 __ 11 13 2 __ – __ 19 11 13 2 Think: __ rounds to 1 and __ rounds to 0. 19 11 1– 0 =1 13 2 __ – __ is about 1. 19 11 Course 1

Estimating Fraction Sums 4 -9 and Differences You can also estimate by rounding mixed numbers. You compare each mixed number to the 1 __ two nearest whole numbers and the nearest 2. 3 1 __ __ Does 10 10 round to 10, 10 2 , or 11? 3 10 1 2 10 __ 10 1 __ 2 __ 10 10 • 10 __ 4 __ 10 10 11 6 __ 7 __ 8 __ 9 __ 10 10 1 3 __ __ The mixed number 10 10 rounds to 10 2. Course 1

Estimating Fraction Sums 4 -9 and Differences Additional Example 2 A: Sports Application The table shows the distances Tosha walked. About how far did Tosha walk on Tuesday and Thursday? 1 __ 5 10 +4 7 __ 8 5 + 5 = 10 She walked about 10 miles on Tuesday and Thursday. Course 1

Estimating Fraction Sums 4 -9 and Differences Additional Example 2 B: Sports Application The table shows the distances Tosha walked. About how much farther did Tosha walk on Sunday than Thursday? 7 8 9 8 __ – 4 __ 10 9– 5=4 She walked about 4 miles farther on Sunday than on Thursday. Course 1

Estimating Fraction Sums 4 -9 and Differences Additional Example 2 C: Sports Application The table shows the distances Tosha walked. Estimate the total distance Tosha walked on Thursday, Saturday, and Sunday. 3 9 7 + 6 __ 4 __ + 8 __ 8 7 1 2 10 1 2 5 + 6 __ + 9 = 20 __ 1 __ miles 2 She walked about 20 Saturday, and Sunday. Course 1 on Thursday,

Estimating Fraction Sums 4 -9 and Differences Check It Out: Example 2 A The table shows the distances Jerry roller skated. About how far did Jerry skate on Tuesday and Sunday? 1 __ 3 5 +2 6 __ 7 3+3=6 Jerry’s Roller Skating Distances Day Distance (mi) 1 __ Tuesday 3 5 Thursday 6 7 Saturday 1 8 __ 7 Sunday 2 7 3 __ 6 __ He roller skated about 6 miles on Tuesday and Sunday. Course 1

Estimating Fraction Sums 4 -9 and Differences Check It Out: Example 2 B The table shows the distances Jerry roller skated. About how much farther did Jerry skate on Saturday than Tuesday? 1 __ 8 7 – 3 1 __ 5 8– 3=5 Jerry’s Roller Skating Distances Day 1 __ Tuesday 3 5 Thursday 6 7 Saturday 1 8 __ 7 Sunday 2 7 He roller skated about 5 miles farther on Saturday than Thursday. Course 1 Distance (mi) 3 __ 6 __

Estimating Fraction Sums 4 -9 and Differences Check It Out: Example 2 C The table shows the distances Jerry roller skated. Estimate the total distance Tosha walked on Tuesday, Thursday, and Sunday. 6 1 3 __ __ __ 3 +6 +2 7 5 7 1 2 3 + 6 __ + 3 = 12 __ He roller skated about 12 Thursday, and Sunday. Course 1 Jerry’s Roller Skating Distances Day Distance (mi) 1 __ Tuesday 3 5 Thursday 6 7 Saturday 1 8 __ 7 Sunday 2 7 1 __ miles 2 3 __ 6 __ on Tuesday,

Estimating Fraction Sums 4 -9 and Differences Lesson Quiz: Part I Estimate each sum or difference by rounding to 0, , or 1. 3. Course 1 2. 0 4. 1

Estimating Fraction Sums 4 -9 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 Course 1