Greatest Common Factor and Least Common Multiple of Whole Numbers

If two numbers are 28 and 42, what is their GCF?

• 7

• 14

• 21

• 28

What is the greatest common factor of 24 and 36?

• 6

• 8

• 12

• 18

Find the greatest common factor of 20 and 30.

• 2

• 5

• 10

• 15

What is the GCF of 8 and 10?

• 1

• 3

• 4

• 2

Which of the following represents all the common factors of 18 and 30?

• 1, 2, 3, 6

• 1, 2, 3, 4

• 1, 2, 4, 6

• 1, 3, 4, 6

Find the common factors of 18 and 24.

• 1, 2, 3, 6

• 1, 2, 4, 6

• 1, 3, 6, 9

• 1, 2, 3, 9

Answer explanation

To find the common factors of 18 and 24, we list their factors: 18 (1, 2, 3, 6, 9, 18) and 24 (1, 2, 3, 4, 6, 8, 12, 24). The common factors are 1, 2, 3, and 6, making the correct choice 1, 2, 3, 6.

Tags

CCSS.4.OA.B.4

Which of the following is a common factor of 6 and 9?

• 1

• 2

• 3

• 4

Answer explanation

The common factors of 6 and 9 are the numbers that divide both evenly. The factors of 6 are 1, 2, 3, and 6. The factors of 9 are 1, 3, and 9. The only common factor is 3, making it the correct answer.

Tags

CCSS.4.OA.B.4

Using prime factorization, find the GCF of 48 and 64.

• 8

• 12

• 16

• 32

Which of the following is NOT a common factor of 24, 48, and 72?

• 4

• 6

• 12

• 48

What are the common factors of 24 and 36?

• 2, 3, 5, 7, 11, 13

• 1, 2, 3, 4, 6, 12

• 1, 2, 4, 8, 12, 24

• 5, 10, 15, 20, 25, 30