Transcript Math L 4-1

Five-Minute Check (over Chapter 3)
Main Idea and Vocabulary
Example 1: Identify Common Factors
Example 2: Find the GCF by Listing Factors
Example 3: Find the GCF by Using Prime Factors
Example 4: Use the GCF to Solve a Problem
Example 5: Use the GCF to Solve a Problem
• Find the greatest common factor of two or more
numbers.
• Venn diagram
• common factor
• greatest common factor (GCF)
Identify Common Factors
Identify the common factors of 20 and 36.
First, list the factors by pairs for each number.
Circle the
common
factors.
Answer: The common factors are 1, 2, and 4.
Identify the common factors of 24 and 42.
A. 1, 2, and 3
B. 1, 6, and 12
C. 1, 2, 3, and 6
D. 1, 2, 3, 6, and 8
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Find the GCF by Listing Factors
Find the GCF of 36 and 48.
First, make an organized list of the factors for each
number.
36: 1 × 36, 2 × 18, 3 × 12, 4 × 9, 6 × 6 → 1, 2, 3, 4, 6, 9,
12, 18, 36
48: 1 × 48, 2 × 24, 3 × 16, 4 × 12, 6 × 8 → 1, 2, 3, 4, 6, 8,
12, 16, 24, 48
The common factors are 1, 2, 3, 4, 6, and 12, and the
greatest of these is 12. So, the greatest common factor
or GCF of 36 and 48 is 12.
Find the GCF by Listing Factors
Use a Venn diagram to show the factors. Notice that
the factors 1, 2, 3, 4, 6, and 12 are the common factors
of 36 and 48 and the GCF is 12.
Answer: The GCF is 12.
Find the GCF of 45 and 75.
A. 3
B. 5
C. 9
D. 15
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Find the GCF by Using Prime Factors
Find the GCF of 52 and 78.
Method 1
Write the prime factorization.
2 and 13
are common
factors.
Find the GCF by Using Prime Factors
Method 2
Divide by prime numbers.
Divide both 52 and 78 by 2.
Divide the quotients by 13.
Using either method, the common prime factors are 2
and 13.
Answer: So, the GCF of 52 and 78 is 2 × 13 or 26.
Find the GCF of 64 and 80.
A. 4
B. 8
C. 16
D. 32
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Use the GCF to Solve a Problem
SALES Anna sells bags of different kinds of
cookies. She made $27 selling bags of peanut butter
cookies, $18 from chocolate chip cookies, and $45
selling bags of oatmeal cookies. Each bag of
cookies costs the same amount. What is the most
that Anna could charge for each bag of cookies?
factors of 18:
1, 2, 3, 6, 9, 18
factors of 27:
1, 3, 9, 27
factors of 45:
1, 3, 5, 9, 15, 45
List all the factors of
each number. Then
find the greatest
common factor.
The GCF of 18, 27, and 45 is 9.
Answer: So, the most she could charge for each bag
is $9.
CANDY Sarah made boxes of different kinds of
candy for a school fund-raiser. She made $24 selling
boxes of hard candy, $40 from taffy, and $64 from
chocolates. Each box of candy cost the same
amount. What is the most that Sarah could charge for
each box of candy?
A. $6
B. $8
C. $10
D. $12
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Use the GCF to Solve a Problem
SALES Anna sells bags of different kinds of
cookies. She made $27 selling bags of peanut butter
cookies, $18 from chocolate chip cookies, and $45
selling bags of oatmeal cookies. How many bags
could Anna have sold if each bag costs $9?
Anna has a total of $27 + $18 + $45 or $90. So, the
number of bags sold is $90 ÷ $9 or 10.
Answer: 10 bags
Interactive Lab:
Greatest Common Factor
CANDY Sarah made boxes of different kinds of
candy for a school fund-raiser. She made $24 selling
boxes of hard candy, $40 from taffy, and $64 from
chocolates. How many boxes could Sarah have sold
if each box costs $8?
A. 8 boxes
B. 11 boxes
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3.
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C. 13 boxes
D. 16 boxes
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End of the Lesson
Five-Minute Check (over Chapter 3)
Image Bank
Math Tools
Animation Menu
Greatest Common Factor
4-2
Equivalent Fractions
4-9
Ordered Pairs and Functions
(over Chapter 3)
Find 43.489 + 71.156.
A. 114.745
B. 114.645
C. 114.635
D. 113.345
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(over Chapter 3)
Find 87.49 – 4.239.
A. 83.701
B. 83.260
C. 83.251
D. 83.161
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(over Chapter 3)
Find 2.62 × 4.15.
A. 6.70
B. 10.873
C. 11.9
D. 12.783
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(over Chapter 3)
Find 96.4 ÷ 4.
A. 21.4
B. 21.7
C. 24.1
D. 42.1
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(over Chapter 3)
Find 3.88 ÷ 0.97.
A. 2.4
B. 3.2
C. 3.8
D. 4
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(over Chapter 3)
McKayla bought a picture frame that cost $6.95, a
candle that cost $3.25, and a bottle of lotion that
cost $5.85. Which of the following is the most
reasonable total for the items purchased?
A. $16
B. $18
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C. $20
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