Finding the Greatest Common Factor

What is the greatest common divisor of 20 and 40?

• 10

• 40

• 5

• 20

Which number is a common factor of both 10 and 7?

• 10

• 2

• 1

• 7

What is the greatest common divisor of 10 and 7?

• 7

• 1

• 5

• 10

Which method can be used to find the GCD of 21 and 30?

• Addition

• Prime factorization

• Subtraction

• Division

What is the greatest common divisor of 21 and 30 using factor listing?

• 1

• 3

• 21

• 30

What is the greatest common divisor of 21 and 30 using prime factorization?

• 3

• 1

• 30

• 21

What common factors do 105 and 30 share?

• 3 and 5

• 105 and 30

• 2 and 5

• 3 and 7

What is the GCD of 105 and 30 using prime factorization?

• 15

• 5

• 30

• 105

Which factors are common in the prime factorization of 105 and 30?

• 3 and 5

• 3 and 7

• 2 and 5

• 5 and 7

What is the product of the common prime factors of 105 and 30?

• 15

• 5

• 30

• 105