How do you find common factors?

Answer 1

Example: 30 and 42

List the factors.

1, 2, 3, 5, 6, 10, 15, 30

1, 2, 3, 6, 7, 14, 21, 42

Write down the numbers on both lists.

The common factors of 30 and 42 are 1, 2, 3 and 6.

Answer 2

You list all of the factors of the number and see which numbers are the same.

Example: 30 and 42

1, 2, 3, 5, 6, 10, 15, 30

1, 2, 3, 6, 7, 14, 21, 42

The common factors are 1, 2, 3, 6
List the factors. Example: 36 and 48

The factors of 36 are:

1, 2, 3, 4, 6, 9, 12, 18, 36

The factors of 48 are:

1, 2, 3, 4, 6, 8, 12, 16, 24, 48

The ones on both lists are common factors.

The common factors are:

1, 2, 3, 4, 6, 12