Download Multiply by Multiples of Ten

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Estimate,
round, and manipulate very large (e.g., millions) and
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very small (e.g., thousandths) numbers.
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UNDERLYING SKILLS AND CONCEPTS:
use basic multiplication facts;
understand place value;
multiply with 1-digit multipliers
Multiply by Multiples of Ten
Numbers with a zero in the ones place are multiples of 10.
You can use basic facts and place value to multiply
by multiples of 10.
Multiples of ten end in zero.
To multiply 12 by 10, first multiply 12 ! 1.
10, 20, 30, 40, 50, 60, 70, 80, 90
Then annex a 0 to the product.
12 ! 1 " 12 so 12 ! 10 " 120
To multiply any number by 20, you can multiply in two steps.
Step 1: Since 20 " 2 ! 10, you can first multiply by 2.
Step 2: Then multiply by 10.
The product will have 0 in the ones place. 12 ! 20 " 240
Use the same strategy to multiply by 30, 40, 50, 60, 70, 80, or 90.
1
ly
Multiply
2
There are 144 pencils in one gross.
How many pencils are there in 70 gross?
Find 144 ! 70.
Step 1: Multiply 144 ! 7: 144 ! 7 " 1,008
Step 2: Multiply 1,008 ! 10.
Hint: Annex a zero in the ones place.
1,008 ! 10 " 10,080
There are 10,080 pencils in 70 gross.
page 30
!
ltip
E x am p l E
? ! 30 " (? ! 3) ! 10
" (? ! 3) and annex a 0
Mu
There are 12 rows of seats at a concert.
Each row has 30 seats. How many people can be seated?
Find 12 ! 30 " ?
Remember: 12 ! 30 is the same as 12 ! 3 ! 10.
Step 1: Multiply 12 ! 3:
12 ! 3 " 36
Step 2: Then multiply 36 ! 10.
Hint: Annex a zero in the ones place. 36 ! 10 " 360
So, 360 people can be seated.
Notice that when you annex a zero in the ones place,
all the digits move one place value to the left.
Where am I
going to keep
that many pencils!
Chapter 3 – Lesson 3
E – © CSL Associates, Inc. All rights reserved.
E x am p l E
Name
P RAC T I C E
Find each product.
1.
15
_____3
45
15
30
_______
450
2.
75
_____6
450
75
60
_______
4,500
3.
10
_____7
70
10
70
_______
700
4.
15
_____8
120
15
80
_______
1,200
5.
67
_____2
134
67
20
_______
1,340
6.
125
_____9
1,125
125
90
_______
11,250
7.
38
_____4
152
38
40
_______
1,520
8.
18
_____5
90
18
50
_______
900
9.
893
_____7
6,251
893
70
_______
62,510
10.
525 11.
419 12.
375 13.
815 14.
523 15.
824
30
70
40
10
50
60
_______
_______
_______
_______
_______
_______
15,750
29,330
15,000
8,150
26,150
49,440
E – © CSL Associates, Inc. All rights reserved.
Solve. Show your work.
16. Jose has $98 in dimes. How many
17. A store sold 40 reams of paper. Each
dimes is that?
ream has 500 sheets.
How many sheets of paper is that?
980
20,000
Circle the correct choice.
18. How many minutes are there in 1 day?
A
B
24
Math
Reasoning
60
C
1,240
D
1,440
Number Sense
MR 2.6, 3.3
19. Describe how to use basic facts and multiples of 10 to
multiply 20 500.
Possible answer: You know that 20 2 10. Since
2 500 1,000, 20 500 10,000. You annex a zero in the
ones place and adjust the comma to show the thousands.
Chapter 3 – Lesson 3
page 31
MCX94.HW.CL.G5.FM&Lesson.v211
8/2/04
18:02
Page 22
Name
…at home!
P RAC T I C E
Find each product.
1.
12
_____3
36
12
30
_______
360
2.
85
_____6
510
85
60
_______
5,100
3.
20
_____7
140
20
70
_______
1,400
4.
14
_____8
112
14
80
_______
1,120
5.
58
_____2
116
58
20
_______
1,160
6.
116
_____9
1,044
116
90
_______
10,440
7.
27
_____4
108
27
40
_______
1,080
8.
19
_____5
95
19
50
_______
950
9.
785
_____7
5,495
785
70
_______
54,950
10.
485 11.
318 12.
425 13.
775 14.
481 15.
862
30
70
40
10
50
60
_______
_______
_______
_______
_______
_______
14,550
22,260
17,000
7,750
24,050
51,720
Solve. Show your work.
17. A store sold 60 reams of paper. Each
dimes is that?
ream has 500 sheets.
How many sheets of paper is that?
760
30,000
Circle the correct choice.
18. How many minutes are there in 3 days?
A
B
1,230
Math
Reasoning
1,440
C
1,443
Number Sense
D
4,320
MR 2.6, 3.3
19. Describe how to use basic facts and multiples of 10 to
multiply 50 200.
50 5 10 and 200 2 100 so 50 200 5 2 10 100.
5 2 10 so 5 2 10 100 10 10 100.
10 10 100 100 100 10,000.
page 22
Home Resource and Homework
Chapter 3 Lesson 3
E – © CSL Associates, Inc. All rights reserved.
16. Miguel has $76 in dimes. How many
MCX94TEG5CH01_32.v7.4.2 2/24/01 19:42 Page 59
Name
P RAC T I C E
Find each product.
1.
15
_____3
45
15
30
_______
450
2.
75
_____6
450
75
60
_______
4,500
3.
10
_____7
70
10
70
_______
700
4.
15
_____8
120
15
80
_______
1,200
5.
67
_____2
134
67
20
_______
1,340
6.
125
_____9
1,125
125
90
_______
11,250
7.
38
_____4
152
38
40
_______
1,520
8.
18
_____5
90
18
50
_______
900
9.
893
_____7
6,251
893
70
_______
62,510
10.
525 11.
419 12.
375 13.
815 14.
523 15.
824
30
70
40
10
50
60
_______
_______
_______
_______
_______
_______
15,750
29,330
15,000
8,150
26,150
49,440
E – © CSL Associates, Inc. All rights reserved.
Solve. Show your work.
16. Jose has $98 in dimes. How many
17. A store sold 40 reams of paper. Each
dimes is that?
ream has 500 sheets.
How many sheets of paper is that?
980
20,000
Circle the correct choice.
18. How many minutes are there in 1 day?
A
B
24
Math
Reasoning
60
C
1,240
D
1,440
Number Sense
MR 2.6, 3.3
19. Describe how to use basic facts and multiples of 10 to
multiply 20 500.
Possible answer: You know that 20 2 10. Since
2 500 1,000, 20 500 10,000. You annex a zero in the
ones place and adjust the comma to show the thousands.
Chapter 3 – Lesson 3
Student Book Page
page 31
Name
…at home!
P RAC T I C E
Find each product.
1.
12
_____3
36
12
30
_______
360
2.
85
_____6
510
85
60
_______
5,100
3.
20
_____7
140
20
70
_______
1,400
4.
14
_____8
112
14
80
_______
1,120
5.
58
_____2
116
58
20
_______
1,160
6.
116
_____9
1,044
116
90
_______
10,440
7.
27
_____4
108
27
40
_______
1,080
8.
19
_____5
95
19
50
_______
950
9.
785
_____7
5,495
785
70
_______
54,950
10.
485 11.
318 12.
425 13.
775 14.
481 15.
862
30
70
40
10
50
60
_______
_______
_______
_______
_______
_______
14,550
22,260
17,000
7,750
24,050
51,720
Solve. Show your work.
17. A store sold 60 reams of paper. Each
dimes is that?
ream has 500 sheets.
How many sheets of paper is that?
760
30,000
Circle the correct choice.
18. How many minutes are there in 3 days?
A
B
1,230
Math
Reasoning
1,440
C
1,443
Number Sense
D
4,320
MR 2.6, 3.3
19. Describe how to use basic facts and multiples of 10 to
multiply 50 200.
50 5 10 and 200 2 100 so 50 200 5 2 10 100.
5 2 10 so 5 2 10 100 10 10 100.
10 10 100 100 100 10,000.
page 22
Home Resource and Homework
Chapter 3 Lesson 3
E – © CSL Associates, Inc. All rights reserved.
16. Miguel has $76 in dimes. How many