1 and 3
6
30
The factors of 18 are 1, 2, 3, 6, 9, 18. For them to be common, they need to be compared to another set of fators.
No
The factors of 6 are: 1, 2, 3 and 6
6 28
18
24
21
Common factors of 35 and 49 are 1 and 7
Any multiple of 6.
12 and any of its multiples