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Practice B
3-6 Multiplying Decimals
Find each product.
1.
0.7
" 0.3
!!
2. 0.05
" 0.4
!!
3.
8.0
" 0.02
!!!
4.
3.5
"
0.2
!!
5.
6.
9.0
"
0.9
!!
12.1
"
0.01
!!!
7. 0.04 • 0.58
8. 2.15 • 1.5
9. 1.73 • 0.8
10. 6.017 • 2.0
11. 3.96 • 0.4
12. 0.7 • 0.009
Evaluate 8x for each value of x.
13. x ! 0.5
14. x ! 2.3
15. x ! 0.74
16. x ! 3.12
17. x ! 0.587
18. x ! 14.08
19. The average mail carrier walks
4.8 kilometers in a workday. How far
do most mail carriers walk in a 6-day
week? There are 27 working days in
July, so how far will a mail carrier
walk in July?
Copyright © by Holt, Rinehart and Winston.
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20. A deli charges $3.45 for a pound
of turkey. If Tim wants to purchase
2.4 pounds, how much will it cost?
58
Holt Middle School Math Course 1
Practice A
3-6 Multiplying Decimals
Exploration Recording Sheet
3-6 Multiplying Decimals
LESSON
LESSON
Find each product.
When you multiply decimals, you can use estimation to help you
determine the position of the decimal point in the product.
1.
0.4
! 0.2
!!
4.
1.1
! 0.9
!!
Estimate each product to the nearest whole number. Then use
a calculator to see how reasonable your estimate is.
4.235 ! 16.9
1.
Estimate
Actual
4(17) " 68
71.5715
443.04
2.
0.78 ! 568
3
!!(600) " 450
4
3.
56.1 ! 23
60(20) " 1200
1290.3
4.
15.6 ! 2.15
16(2) " 32
33.54
2.
0.3
! 0.4
!!
5.
2.5
! 0.5
!!
0.08
Estimate each product. Use this estimation to decide where to
place a decimal point in the answer. Check with your calculator.
6.0
! 0.7
!!
1.25
0.2
1.8
11. 9.6 • 0.2
2.68
6. 0.75 ! 692 " 5 1 9.0
6.
0.6
4.2
8. 1.2 • 1.5
10. 6.7 • 0.4
5. 70.5 ! 4.4 " 3 1 0.2
1.2
! 0.5
!!
0.12
0.99
7. 0.4 • 0.5
3.
9. 1.7 • 0.3
0.51
12. 0.8 • 0.8
1.92
0.64
Evaluate 2x for each value of x.
7. 56 ! 3.125 " 1 7 5.0
13. x " 0.1
8. 45.6 ! 2.15 " 9 8.0 4
14. x " 0.5
0.2
9. 4.17 ! 1.2 " 5.0 0 4
10. 125.2 ! 7.4 " 9 2 6.4 8
16. x " 1.2
Think and Discuss
1.0
Possible answer: Round up or down to a compatible number, and multiply.
12. Explain how you know where to place the decimal point
in a product.
1.8
17. x " 1.7
2.4
11. Discuss your strategies for estimating in Exercises 1– 4.
15. x " 0.9
18. x " 2.4
3.4
4.8
19. Each box can hold 2.5 pounds of
apples. How many pounds can
3 boxes hold?
20. Each pie costs $5.60. How much will
it cost to buy 2 pies?
7.5 pounds
$11.20
Possible answer: The estimate gives you an idea of what the answer
should be so you can place the decimal.
56
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Holt Middle School Math Course 1
Practice B
3-6 Multiplying Decimals
LESSON
Find each product.
Find each product.
0.7
! 0.3
!!
4.
3.5
!
0.2
!!
2. 0.05
! 0.4
!!
0.21
3.
8.0
! 0.02
!!!
6.
9.0
!
0.9
!!
0.02
5.
1. 9.86
! 0.3
!!
2.958
0.16
12.1
!
0.01
!!!
2. 12.01
! 0.46
!!!
4. 11.65 • 0.23
0.121
8.1
7. 0.04 • 0.58
8. 2.15 • 1.5
9. 1.73 • 0.8
0.0232
3.225
1.384
10. 6.017 • 2.0
11. 3.96 • 0.4
12. 0.7 • 0.009
12.034
1.584
0.0063
7. 0.058 • 0.129
0.007482
5.5246
4
10. x = 1.9
16. x " 3.12
24.96
5.92
17. x " 0.587
18. x " 14.08
4.696
19. The average mail carrier walks
4.8 kilometers in a workday. How far
do most mail carriers walk in a 6-day
week? There are 27 working days in
July, so how far will a mail carrier
walk in July?
0.2115
32.3
190.655
0.90798
16. 2.97n for n " 1.8
112.64
8. 29.864 • 5.13
0.085
107.219
14. x = 2.059
15. x = 75.844
35.003
1,289.348
17. 122 # 1.9c for c " 3.7
151.03
19. 1.6t # 3.056 for t " 2.09
6.4
20. One year on Mercury is equal to 87.97 21. One year on Earth is equal to
Earth days. One year on Pluto is three
365.30 days. One year on Mars is
times the length of one Mercury year
twice the length of one Earth year
minus 16.21 days. How long is one
minus 43.6 days. How long is one
year on Pluto?
year on Mars?
$8.28
247.7 days
Copyright © by Holt, Rinehart and Winston.
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0.40344
12. x = 6.307
341.92
58
9. 100.86 • 0.004
153.20232
5.346
18. 73 $ 2x for x " 0.54
129.6 kilometers
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
33.18855
Evaluate.
20. A deli charges $3.45 for a pound
of turkey. If Tim wants to purchase
2.4 pounds, how much will it cost?
28.8 kilometers;
6. 11.405 • 2.91
11. x = 0.005
13. x = 11.215
15. x " 0.74
18.4
7.05
! 0.03
!!!
Evaluate 17x for each value of x.
Evaluate 8x for each value of x.
14. x " 2.3
3.
5. 24.54 • 0.037
2.6795
0.7
13. x " 0.5
Holt Middle School Math Course 1
Practice C
3-6 Multiplying Decimals
LESSON
1.
57
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All rights reserved.
Holt Middle School Math Course 1
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
123
687 days
59
Holt Middle School Math Course 1
Holt Middle School Math Course 1