Question

Find the GCF of 21, 30

Answer 1

3

Explanation:

Factors of 21: 1, 3, 7, 21

Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30

The GCF is the largest factor they both have.

GCF = 3

Answer 2

The GCF of 21 and 30 is 3.

Explanation:

Find the prime factorization of 21

21 = 3 × 7

Find the prime factorization of 30

30 = 2 × 3 × 5

To find the gcf, multiply all the prime factors common to both numbers:

Therefore, GCF = 3