Transcript Document

Five-Minute Check (over Lesson 8–7)
Main Idea and Vocabulary
Example 1: Find Common Factors
Example 2: Numbers with One Common Factor
Example 3: Find the Greatest Common Factor
Example 4: Use the Greatest Common Factor
• I will identify common factors of a set of whole
numbers.
• common factor
• greatest common factor (GCF)
Find Common Factors
Find the common factors of 12 and 18.
Step 1 List all the factors of each number.
12 = 1 × 12
12 = 2 × 6
12 = 3 × 4
factors of 12: 1, 2, 3, 4, 6, 12
18 = 1 × 18
18 = 2 × 9
factors of 18: 1, 2, 3, 6, 9, 18
18 = 3 × 6
Find Common Factors
Step 2 Find the common factors.
factors of 12: 1, 2, 3, 4, 6, 12
factors of 18: 1, 2, 3, 6, 9, 18
Answer: The common factors are 1, 2, 3, and 6.
Which lists the common factors of 15 and 21?
A. 1, 3
B. 1, 2, 3
C. 1, 3, 5
D. 1, 3, 5, 7
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Numbers with One Common Factor
Find the common factors of 8, 14, and 21.
factors of 8:
1, 2, 4, 8
factors of 14: 1, 2, 7, 14
factors of 21: 1, 3, 7, 21
Answer: The only factor common to all three numbers
is 1.
Find the common factors of 6, 15, and 23.
A. 1, 2, 3, 6
B. 1, 3, 5
C. 1, 3
D. 1
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Find the Greatest Common Factor
Find the greatest common factor of 12, 16,
and 18.
List all of the factors of 12, 16, and 18 to find the
common factors.
factors of 12: 1, 2, 3, 4, 6, 12
factors of 16: 1, 2, 4, 8, 16
factors of 18: 1, 2, 3, 6, 9, 18
The common factors are 1 and 2. The greatest
of these is 2.
Find the Greatest Common Factor
Answer: So, the greatest common factor, or GCF,
of 12, 16, and 18 is 2.
Find the greatest common factor of 5, 15, and 25.
A. 2
B. 3
C. 4
D. 5
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Use the Greatest Common
Factor
Olimpia is making a vegetable platter using
32 tomato slices and 48 cucumber slices. She
wants to put an equal number of tomato slices
and an equal number of cucumber slices on each
plate. What is the greatest number of plates she
can make?
First, find the common factors of each number.
factors of 32: 1, 2, 4, 8, 16, 32
factors of 48: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48
common factors of 32 and 48: 1, 2, 4, 8, 16
Use the Greatest Common
Factor
Olimpia can make 1, 2, 4, 8, or 16 plates with each plate
having an equal number of tomato slices and an equal
number of cucumber slices.
Answer: Since 16 is the GCF, the greatest number
of plates Olimpia can make is 16.
Check There will be 32 ÷ 16, or 2 tomato slices and
48 ÷ 16 or 3 cucumber slices on each plate.
Serena is making two appetizers for her party. She
has 48 mini meatballs and 56 crackers with cheese.
She wants to put the same number of appetizers on
each serving plate. What is the greatest number of
plates she can make?
A. 1 plate
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B. 4 plates
End of the Lesson
Five-Minute Check (over Lesson 8–7)
Image Bank
Math Tool Chest
Compare Fractions
(over Lesson 8–7)
Use any strategy to solve.
Jake went to see a play at his high school. It
started at 6:35 P.M. and lasted 1 hour and
55 minutes. At what time did the play end?
A. 9:25 A.M.
B. 8:30 P.M.
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D. 7:00 P.M.
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C. 8:45 P.M.
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