1,2
Just 1.
-9
1,2,7,14 1,5,7,35
42
The common factors of 30 and 40 are 1, 2, 5, 10
The common factors of 30 and 21 are 1 and 3.
The common factors of 30 and 63 are 1 and 3.
The common factors of 30 and 32 are: 1 and 2
The common factors of 30 and 74 are: 1 and 2.
The common factors of 25 and 30 are 1 and 5.
210
23 and 30 share no common factors aside from 1.