Answer Key
Chapter 2 – Using Decimals 2.1
Decimal Comparisons without Rounding
Answers 1. <
2. >
3. >
4. <
5. >
6. <
7. <
8. <
9. >
10. 373.129, 373.192, 373.219, 373.291 11. .4674, .4754, .4755, .4764 12. 7.06, 7.16, 7.2, 7.21 13. 25.074, 25.407, 25.417, 25.741 14. 15.0001, 15.001, 15.067, 15.100 15. 6.008, 6.087, 6.780, 6.870
2.2
Decimal Rounding Given Place Value
Answers 1. 622
2. 1,318
3. 17
4. 50
6. 350
7. 16, 789
8. 13
9. 146
10. 32.30
11. .1062
12. 2.40047
13. 4,062.0
14. .1238
15. 3.457
2.3
5. 124
Decimal Comparisons with Rounding
Answers 1. =
2. =
3. <
4. >
5. >
6. <
7. =
8. =
9. <
10. 2.033, 2.034, 2.035, 2.039 11. 16.088, 16.089, 16.089, 16.100 12. 3.821, 3.822, 3.828, 3.829 13. .056, .057, .058, .060 14. .7, .8, .9, 1.0, 2.0 15. $54.00 two person, $68.00 Three Person, $90 Four person The best estimate is for 2 – three person units to be rented
CK-12 Middle School Math Concepts - Grade 7
1
Answer Key
Chapter 2 – Using Decimals 2.4
Decimal Addition
Answers 1. 740.811
2. 1.9445
3. 55.92
4. 79.604
5. 72.556
6. 112.5
7. 1521.2
8. 11.1
9. 1.9
10. 10.4
11. 610.61
12. 8.46
13. 335.78
14. 2.05
15. 4.77
2.5
Decimal Addition Using Front- End Estimation
Answers 1. 6.8
2. 6.2
3. 10.9
4. 11
5. 6.9
6. 17.5
7. 15.5
8. 14.5
9. 39
10. 43.7
11. 37.3
12. 39.4
13. 1.0
14. 13.1
2.6
15. 1.6
Commutative Property of Addition with Decimals
Answers 1. Associative
2. Commutative
3. Associative
4. Commutative
5. Commutative
6. Associative
7. Commutative
8. Associative
9. .292
10. 2.115
11. .306
12. 6.174
13. 1.08
14. $50.50
15. 61.2 yards
2.7
Decimal Subtraction
Answers 1. .82
2. .0386
3. 12.5034
4. 11.94
5. 191.4
6. 8.146
7. 75.75
8. .7669
9. 788.244
10. 101.76
11. 12.88
12. .18
13. 699.97
14. .33
15. .97
CK-12 Middle School Math Concepts - Grade 7
2
Answer Key
Chapter 2 – Using Decimals 2.8
Decimal Subtraction Using Front- End Estimation
Answers 1. 2.2
2. 1.0
3. 6.9
4. 6.4
5. 1.2
6. 9.1
7. 1.1
8. 10.2
9. .2
10. .5
11. .6
12. .4
13. .3
14. 4.1
15. .1
2.9
Inverse Property of Addition in Decimal Equations
Answers 1. 4.62
2. 11.58
3. 10.05
4. 2.952
5. 65.82
6. 45.32
7. 78.35
8. 5.78
9. 69.11
10. 204.495
11. 45.68
12. 1.6 pounds
13. 6.495 km
14. $32.49
15. 8.5 Liters
2.10
Decimal Multiplication
Answers 1. 10.16
2. .1656
3. 20.3406
4. 18.432
5. 19.2814
6. 1.935
7. 9.6252
8. 172.12
9. 6.51
10. 22.54
11. 100
12. 65.7
13. 10.56
14. 61.88
15. 80.91
2.11
Estimation to Check Decimal Multiplication
Answers 1. 6.9
2. 124.2
3. .0624
4. 539.5
5. 5.488
6. 9.49
7. 5.44
8. .51
9. .4611
10. .3724
11. 24.75
12. 132
13. 294
14. .0099
15. 70.3
CK-12 Middle School Math Concepts - Grade 7
3
Answer Key
Chapter 2 – Using Decimals 2.12
Commutative Property of Multiplication with Decimals
Answers 1. 37.048p
2. 100.068q
3. 330.12x
4. 14.84r
5. 21.28x
6. 6.72y
7. 20.77x
8. 20.493r
9. 15.876y
10. 9.966x
11. 15.68x
12. 29.44y
13. 10.35x
14. 197.12x
15. 259.86y
2.13
Decimal Division
Answers 1. 1.2
2. 1.3
3. 1.5
4. 2
5. 14.7
6. 1.6
7. 8.8
8. 10.3
9. 7.5
10. 4.9
11. 4.50
12. 12.79
13. 244.90
14. 2.04
15. 3.57
2.14
Estimation to Check Decimal Division
Answers 1. 70
2. .3
3. 20
4. 4
5. 14.4
6. 2.8
7. 2.9
8. 2
9. 3.7
10. 5.1
11. 3.9
12. 5.4
13. 5
14. 8.7
15. .2
2.15
Division to Solve Decimal Equations
Answers 1. 2.1
2. 3.3
3. 4.1
4. 4.2
5. 5.6
6. 2.5
7. 6.3
8. 6.3
9. 6.8
10. 9.6
11. .581
12. 11.7
13. 5.5 km
14. 6.8 m
15. 96.54 kilometers per hour
CK-12 Middle School Math Concepts - Grade 7
4
Answer Key
Chapter 2 – Using Decimals 2.16
Scientific Notation
Answers 1. 5.6 x 10-9
2. 2.4 x 1010
3. 9.6 x 1017
4. 1.2 x 10-7
5. 3.6 x 107
6. 9.8 x 10-4
7. 3.4 x 10-8
8. 3.45 x 108
9. 380,800,000,000
10. .0000021
11. 591,200,000
12. .00000678
14. .000045
15. 32,100,000
13. 5,700,000,000
2.17
Comparison of Numbers in Scientific Notation
Answers 1. >
2. <
3. >
4. <
5. >
7. >
8. <
9. >
10. <
11. >
6. >
12. 2.1 x 1020, , 6.4 x 1015, 1.7 x 1015, 9.2 x 1010 13. 8.71 x 10-3, 4.16 x 10-3, 5.63 x 10-5, 3.42 x 10-6 14. .000202, .0000221, .000212, .0000202 15. 8.61 x 108, 86,120,000, 86,102,000, 8.61 x 107
2.18
Operations with Numbers in Scientific Notation
Answers 1. 8.8 x 103
2. 4.1 x 104
4. 8 x 103
5. 32.64 x 106
6. 6.2 x 102
7. 9.8 x 105
8. 2.1 x 103
9. 10.1 x 103
10. 3.96 x 106
11. 4.1 x 102
12. 274.6 x 10-6
13. 1.64 x 104
14. 9.728 x 103
3. 12.1 x 105
15. .71 x 103
CK-12 Middle School Math Concepts - Grade 7
5
Answer Key
Chapter 2 – Using Decimals 2.19
Metric System
Answers 1. 10 m
2. 1,000,000 cL
3. 1000 cg
4.10 cL
5. .0002 kg
6. .2 m
7. .002 kL
8. .02 kg
9. 1.8076 m
10. 1807.6 mm
11. .0018076 km
12. 490.9 L
13. 49,090 cL
14. 490,900 ML
15. 1000
2.20
Appropriate Tools for Metric Measurement
Answers 1. graduated cylinder
2. Metric tape
3. Scale
4. Graduated cylinder
5. kilometer
6. Gram
7. Centimeter
8. Milliliter
9. kilograms
10. Kilograms
11. Meter
12. 113.4 meters
13. 3.525 liters
14. Max, Taboo, Arnaud, Josie
2.21
15. 1800 grams
Conversions of Length, Mass and Capacity in Metric Units
Answers 1. 100 mm
2. 100,000 m
3. .453 km
4. 1,567,000 m
5. 67 m
6. 780 cm
7. 65,570 mL
8. 282.03 mL
9. 9761 mL
10. 2946.7 centigrams
11. .00562 centigrams
12. 4505.84 centigrams
13. .08996 kiloliters
14. .045217 kiloliters
15. 31.20700 kiloliters
CK-12 Middle School Math Concepts - Grade 7
6
Answer Key
Chapter 2 – Using Decimals 2.22
Comparison of Metric Measurement
Answers 1. >
2. <
3. >
4. <
5. <
6. >
8. >
9. <
10. <
11. >
12. =
13. >
7. >
14. 7,938,200 mg, 7,838,200 cg, 79,382 g, 79,282 kg 15. 21.06 kL, 21,061 L, 21,161,000 mL, 2,261,000
2.23
Estimation of Conversion to Metric Units
Answers 1. 1.18 Liters
2. 4.57 meters
3. 152.4 mm
4. 6.08 kg
5. .24 Liters
6. .004 km
7. 152.4 cm
8. 365.76 cm
9. 203.2 mm
10. 807.96 grams
11. 298.45 mm
12. 7.57 Liters
13. 6.80 kilograms
14. 1.05 km
15. Computer
CK-12 Middle School Math Concepts - Grade 7
7
