Greatest Common Factor Review

Greatest Common
Factor

Finding the GCF

The GCF of two or more numbers is the largest factor that the numbers share. Follow the example to the right.

Finding the GCF

Find the GCF of 18 and 45

First, find all of the factors of each number
18: 1, 2, 3, 6, 9, 18
45: 1, 3, 5, 9, 15, 45

Next, look for the common factors and find the largest one.
18: 1, 2, 3, 6, 9, 18
45: 1, 3, 5, 9, 15, 45

THE GCF is 9

Multiple Choice

What is the greatest common factor of 32 and 48?

• 40
• 24
• 8
• 16

Multiple Choice

What is the greatest common factor for 25 and 40?

• 5
• 8
• 3
• 12

Multiple Choice

What is the greatest common factor of 38 and 22?

• 3
• 5
• 7
• 2

Find the GCF of 6, 12 and 48

First, find all of the factors of each number
6: 1, 2, 3, 6
12: 1, 2, 3, 4, 6, 8, 24, 48
48: 1, 2, 3, 4, 6, 8, 12, 16,24, 48
Next, look for common factors among the 3 numbers and find the largest one.
6: 1, 2, 3, 6
12: 1, 2, 3, 4, 6, 8, 24, 48
48: 1, 2, 3, 4, 6, 8, 12, 16,24, 48

THE GCF
is 6

Multiple Choice

What is the greatest common factor among 9, 27 and 36?

• 9
• 18
• 12
• 24

Multiple Choice

What is the greatest common factor among 7, 14 and 56?

• 2
• 10
• 21
• 7

Multiple Choice

Which of the following is not a factor of 12?

• 1

• 6

• 8

• 3

Multiple Choice

Which of the following NOT a factor of 36

• 1

• 9

• 12

• 13

Multiple Choice

What is the greatest common factor among 6, 14 and 18?

• 3
• 2
• 4
• 5

Multiple Choice

What is the GCF of 9 and 4?

• 0

• 1

• 3

• 5

Multiple Choice

What is the GCF of 56 and 80?

• 8

• 4

• 2

• 1

Multiple Choice

What does GCF stand for?

• Least Common Factor

• Greatest Common Factor

• Gray Cats Flying

• Grand Carousel Factors

Multiple Choice

Which type of numbers have only 2 factors, 1 and itself?

• prime

• composite

• even

• odd

Multiple Choice

What are the numbers you multiply to get a product?

• even

• odd

• factors

• multiples