What numbers can go into 63 and 210?

Answer 1

The factors of 63 are:

1, 3, 7, 9, 21, 63

The factors of 210 are:

1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70, 105, 210

The common factors are:

1, 3, 7, 21

Answer 2

1, 3 and 7.