explore and grow - 5th grade - home · chapter 3 ⎜ lesson 1 85 name estimate the sum or diff...

3.13.1Name Estimate Estimate

Sums and Sums and Diff erencesDiff erencesLearning Target:Learning Target: Use rounding or compatible Use rounding or compatible

numbers to estimate sums and differences of decimals.numbers to estimate sums and differences of decimals.Success Criteria:Success Criteria: • I can use rounding to estimate a sum or difference.• I can use rounding to estimate a sum or difference.• I can use compatible numbers to estimate a sum• I can use compatible numbers to estimate a sum

or difference.or difference.

Explore and Grow

Chapter 3 ⎜ Lesson 1 83

Estimate each sum or diff erence.

Construct Arguments Compare your answers to your partner’sanswers. Explain why they are the same or why they are diff erent.

++ −

23.08

+ 59.55

98.82

− 76.47

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Elem_GR5_SE_Chapter_03.indb 83Elem_GR5_SE_Chapter_03.indb 83 2/6/18 4:06 PM2/6/18 4:06 PM

Think and Grow: Modeling Real LifeThink and Grow: Estimate Sums and Differences

84

Estimate the sum or diff erence.

1. 1. 112.18 + 47.99

2. 2. 68.8 − 29.7

You can use rounding or compatible numbers to estimate sums and diff erences of decimals.

Show and GrowShow and GrowSShhhhhhhoowwwwwwww aannnddddddd GGGGGrrrrrroowwwwwwSSSSSSSShhhhhhhhoooooooowwwwwwww aaaaaaannnnnnnndddddddd GGGGGGGGrrrrrrrroooooooowwwwwwwwShow and GrowShow and Grow

Example Estimate 27.21 + 48.73.

Example Estimate 388.5 − 103.2.

So, 27.21 + 48.73 is about .

So, 388.5 − 103.2 is about .

So, 27.21 + 48.73 is about .

So, 388.5 − 103.2 is about .

One Way: One Way: Use rounding. Round each addend to the nearest whole number. Then fi nd the sum of the rounded numbers.

One Way: One Way: Use rounding. Round each number to the nearest ten.Then find the diff erence of the rounded numbers.

Another Way: Another Way: Use compatibleUse compatiblenumbers.numbers.

Another Way: Another Way: Use compatible Use compatible numbers.numbers.

27.21+ 48.73 +

27.21+ 48.73

+

388.5− 103.2 −

388.5− 103.2

−

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Chapter 3 ⎜ Lesson 1 85

Name


10. 10. Precision Does rounding 209.11 − 104.53 to the nearest ten or to the nearest hundred give an estimate that is closer to the actual diff erence? Explain.

11. 11. DIG DEEPER Newton packs asuitcase to fl y on a plane. His suitcase needs to weigh less than50.0 pounds. Should Newton overestimate or underestimate the weight of his suitcase? Explain.

3. 3. 7.95− 1.72

5. 5. 67.5 + 15.1

7. 7. 13.9 − 8.21

4. 4. 237.5 + 345.1

6. 6. 418.9 − 14.7

8. 8. 208.6 + 56.9

Apply and Grow: Practice

9. 9. Number Sense Descartes estimates a sum by rounding each numberto the nearest ten. His estimate is 140. Which sums could he have estimated?

83.6 + 59.8 106.92 + 44.68 130.8 + 4.68 73.5 + 67.4

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Think and Grow: Modeling Real Life

86

13. 13. One cup of wild rice has 6.5 grams of protein. One cup of shredded chicken has 36.9 more grams of protein than 1 cup of wild rice. About how many grams of protein are in 1 cup of chicken?

14. 14. The speed Earth orbits the Sun is 18.5 miles per second. This speed is 3.3 miles per second slower than the speed Venus orbits the Sun. About how fast does Venus orbit the Sun?

Example About how many feet taller is One World Trade Center than the Empire State Building?

Round the height of each building to the nearest hundred because you do not need a precise answer.

One World Trade Center: 1,800 feetEmpire State Building: 1,500 feet

Subtract the estimated height of the Empire State Building from the estimated height of One World Trade Center.

12. 12. About how many more tons does the African elephant weigh than the hippopotamus?

wo oowo wwwwwoowwwwwrorrrrrrrGGGG GGGGddnnnnnahhhhhhhhoww aanddddddddwwwwwoowwwwwwwhohhhhhSSSSSSS ow nd GGrrowGGGGGrrrrroooooooGGGGGGGGrrrrrrrroooooooowwwwwwwwaaaaannnnndddddaaaaaaaannnnnnnndddddddd SSSSSShhhhoooooooSSSSSSSShhhhhhhhoooooooowwwwwwww Show and GrowShow and Grow

1,800− 1,500

One World Trade Center is about feet taller than the Empire State Building.

African elephant:5.7 tons

Hippopotamus:2.3 tons

1,776.02 ft

One WorldTrade Center

Empire StateBuilding

1,454.16 ft6 ft

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Name 3.13.1Homework

& PracticeLearning Target:Learning Target: Use rounding or compatible Use rounding or compatible numbers to estimate sums and differences of decimals.numbers to estimate sums and differences of decimals.

87Chapter 3 ⎜ Lesson 1

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Example Estimate 734.6 − 285.3.

One Way: One Way: Use rounding. Round each number to the nearest ten. Then fi nd the diff erence of the rounded numbers.

Another Way: Another Way: Use compatible Use compatible numbers.numbers.


1. 1. 76.81+ 2.17

3. 3. 418.44 − 23.61

5. 5. 6.24 − 3.8

4. 4. 90.7 + 2.3

6. 6. 837.51 + 149.27

734.6− 285.3

730− 290

440

734.6− 285.3

750− 300

450

So, 734.6 − 285.3 is about .

So, 734.6 − 285.3 is about .440

450

2. 2. 79.1 − 32.8


88

8. 8. Reasoning Describe a situation when you would estimate the diff erence of 25.4 and 19.8 to the nearest whole number.

7. 7. Open-Ended Write a decimal addition problem that has an estimated sum of 35.

9. 9. Modeling Real Life Your friend participates in a 3.1-mile race. She walks for 1.4 miles of the race and runs the rest. About how many miles does your friend run?

10. 10. DIG DEEPER Your phone has 16,000 megabytes of total storage space. About how much storage space is free?

Review & RefreshFind the sum.

11. 11. 2

— 8

+ 4

— 8

= 12. 12. 1

— 2

+ 5

— 2

= 13. 13. 1 + 1

— 4

=

Storage Space Used

Photos3,111.1 megabytes

Applications5,345.3 megabytes

Music4,598.8 megabytes

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explore and grow - 5th grade - home · chapter 3 ⎜ lesson 1 85 name estimate the sum or diff...

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