Name
LESSON
Date
Class
Problem Solving
3-3 Least Common Multiple
Write the correct answer.
1. Earth revolves around the sun every
year. Jupiter revolves around the sun
every 12 years. If Earth and Jupiter
passed the same point of the sun
sometime in 2002, when will they
pass that point together again?
2. House representatives are elected
every 2 years. The President of the
United States is elected every
4 years. Both will be elected in 2008.
When is the next year after 2008
both will be elected?
3. A cat runs a mile every 2 minutes. A
squirrel runs a mile every 5 minutes.
A cat and a squirrel start together
running around a 1-mile track. How
long will it be before they meet at the
starting point?
4. A car manual recommends changing
the oil every 5,000 miles and
inspecting the engine coolant system
every 15,000 miles. At how many
miles will both be done together for
the first time? for the second time?
Choose the letter for the best answer.
5. Mr. Walters receives a dividend every
5 months and a royalty payment
every 6 months. He received both in
January 2006. When is the next time
he would receive both payments in
the same month?
A January 2007
B April 2008
C July 2006
D July 2008
6. Rag Rite Cloth Store always rounds
amounts less than whole yards up to
the next yard for ribbon purchases. The
ribbon that you want to buy comes in
rolls of 8 feet. How many rolls should
you buy to get the best buy?
F 1 roll
G 2 rolls
H 3 rolls
J 4 rolls
7. The sanitation department picks up
recyclable plastics every 3 days. The
paper recycling center picks up
papers every 4 days. They both
picked up on May 4. When will they
next pick up on the same day?
A May 7
B May 12
C May 11
D May 16
8. Hal and Jess both volunteer at the
local nursing home. Hal volunteers
every 6 days, and Jess volunteers
every 8 days. They were both there
on Monday. In how many days will
they both volunteer together again?
F in 14 days
G in 24 days
H in 48 days
J in 2 days
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
26
Holt Mathematics
Problem Solving
3-3 Least Common Multiple
Challenge
3-3 Multiple Solutions
LESSON
LESSON
Write the correct answer.
Write the two numbers from each box that have the lowest least
common multiple. Then write the LCM.
1.
3.
5.
7.
9.
5 12
Numbers:
6 8
LCM:
2 10
Numbers:
5 3
LCM:
6; 12
2.
2; 3
4.
12
6
4; 6
Numbers:
6 4
6.
12
7 5
LCM:
8 10
Numbers:
6 5
LCM:
15 10
Numbers:
7 8
LCM:
5; 10
8.
10
10; 15
2 7
Numbers:
9 10
LCM:
7 2
Numbers:
10 12
LCM:
30
10
2; 10
Numbers:
15 45
LCM:
24 35
Numbers:
32 14
LCM:
30
14; 35
70
10 minutes
Answer Key
A
T
E
H
70
6
30
12
10
11. What animal copies from the others on a math test?
T
30
H
10
E
12
C
70
H
10
E
12
E
12
T
30
A
6
H
10
9
4
5
8
2
1
10
6
3
7
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
25
Holt Mathematics
5. Mr. Walters receives a dividend every
5 months and a royalty payment
every 6 months. He received both in
January 2006. When is the next time
he would receive both payments in
the same month?
A January 2007
B April 2008
C July 2006
D July 2008
6. Rag Rite Cloth Store always rounds
amounts less than whole yards up to
the next yard for ribbon purchases. The
ribbon that you want to buy comes in
rolls of 8 feet. How many rolls should
you buy to get the best buy?
F 1 roll
G 2 rolls
H 3 rolls
J 4 rolls
7. The sanitation department picks up
recyclable plastics every 3 days. The
paper recycling center picks up
papers every 4 days. They both
picked up on May 4. When will they
next pick up on the same day?
A May 7
B May 12
C May 11
D May 16
8. Hal and Jess both volunteer at the
local nursing home. Hal volunteers
every 6 days, and Jess volunteers
every 8 days. They were both there
on Monday. In how many days will
they both volunteer together again?
F in 14 days
G in 24 days
H in 48 days
J in 2 days
26
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Reading Strategies
3-3 Focus on Vocabulary
Holt Mathematics
Puzzles, Twisters & Teasers
3-3 A Common Cause!
LESSON
LESSON
A multiple of a number is the product of that number and another
factor.
Multiples of 5 are the numbers you get when you multiply by 5.
1•55
2 • 5 10
3 • 5 15
4 • 5 20
The multiples of 5 listed above are 5, 10, 15, 20.
You can continue to count by 5’s to list more multiples of 5: 25, 30,
35, and so on.
Common means something that is shared. A common multiple of two
numbers is a multiple that the two numbers share, or have in common.
Multiples of 5
Multiples of 4
15,000 mi; 30,000 mi
Choose the letter for the best answer.
Use the table at the bottom of the page to solve the riddle. In
the middle row, write the LCM of each exercise above the
exercise number. Then choose the letter from the Answer Key
that matches the LCM and write it in the appropriate box.
C
4. A car manual recommends changing
the oil every 5,000 miles and
inspecting the engine coolant system
every 15,000 miles. At how many
miles will both be done together for
the first time? for the second time?
3; 12
12
LCM:
2012
3. A cat runs a mile every 2 minutes. A
squirrel runs a mile every 5 minutes.
A cat and a squirrel start together
running around a 1-mile track. How
long will it be before they meet at the
starting point?
10; 15
Numbers:
12 7
2. House representatives are elected
every 2 years. The President of the
United States is elected every
4 years. Both will be elected in 2008.
When is the next year after 2008
both will be elected?
2014
10
9 10
10. 3 10
1. Earth revolves around the sun every
year. Jupiter revolves around the sun
every 12 years. If Earth and Jupiter
passed the same point of the sun
sometime in 2002, when will they
pass that point together again?
2; 10
Find the least common multiple for each set of numbers. Spell
out the answers to solve the crossword puzzle.
Across
5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60
4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60
Down
1. 3, 5
1. 3, 9, 15
4. 9, 12
2. 4, 6, 24
6. 10, 4
3. 6, 9
7. 2, 5
5. 4, 7
9. 6, 14
6. 3, 7
8. 15, 20
In the example above, you can see the multiples that are common
to both 4 and 5. They are 20, 40, and 60.
The least common multiple (LCM) of two numbers is the smallest
of the common multiples. 20 is the smallest, or least common,
multiple of 4 and 5.
Answer each question.
1
1. What is a multiple?
by a certain number
2. What does the word common mean?
something that is shared
3. What is a common multiple?
multiples that two numbers share, or have in common
4. What is the least common multiple?
the smallest multiple that two numbers have in common
5. Write the first 9 multiples of 2.
2, 4, 6, 8, 10, 12, 14, 16, 18
6. Write the first 9 multiples of 3.
3, 6, 9, 12, 15, 18, 21, 24, 27
8. What is the least common multiple for 2 and 3?
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
27
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
I
F
2
T
E
3
E
W
I
R
E
G
T
N
H
Y
T
–
Y
F
–
I
F
N
V
E
O
Possible answer: the answers or products when you multiply
7. Write the common multiples for both 2 and 3.
F
9
F
O
7
T
4
N
T
H
I
R
5
T
E
N
T
W
E
N
T
E
E
Y
E
N
–
S
T
E
O
I
Y
I
U
X
–
G
T
W O
H
Y
N
T
T
Y
–
T
Y
S
I
X
E
6
W
R
Y
W
8
–
E
6, 12, and 18
6
Holt Mathematics
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All rights reserved.
68
28
Holt Mathematics
Holt Mathematics