What is the greatest common factor of 8 42 and 60?

Answer 1

The GCF of 8, 42, and 60 is 2.

The factors of 8 are 1, 2, 4, and 8.

The factors of 42 are 1, 2, 3, 6, 7, 14, 21, and 42.

The factors of 60 are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60.

The greatest common factor is 2.

Or, you can look at the prime factors.

The prime factors of 8 are 2, 2, and 2.

The prime factors of 42 are 2, 3, and 7.

The prime factors of 60 are 2, 3, and 5.

The only prime factor they all have in common is 2, so the greatest common factor is 2.

Using factor trees:

8

4,2

2,2,2

42

21,2

7,3,2

60

30,2

15,2,2

5,3,2,2

The GCF is 2.