What are some example of common factors?

Answer 1

Example: 30 and 42
1, 2, 3, 5, 6, 10, 15, 30
1, 2, 3, 6, 7, 14, 21, 42

The common actors are 1, 2, 3 and 6 because they appear on both lists.

Answer 2

1 and 3 are common factors of 6 and 9.

1, 2, 7 and 14 are common factors of 42 and 70.

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