Common factors are found by comparing the factors of sets of numbers. The common factor of any group of consecutive numbers is 1. I suspect you might want to know the factors of those numbers rather than the common factors. If so, ask that question. It has been answered here many times before.
49 and 100 share no common factors aside from 1.
1 and 5 are their only common factors.
The common factors are: 1, 2, 4
Since 100 is a factor of 200, all of its factors are common.
The common factors of 100 and 150 are: 1, 2, 5, 10, 25, and 50
The common factors of 58 and 100 are: 1, 2
49 and 100 share no common factors aside from 1.
The common factors of 16 and 100 are 1, 2 and 4.
The common factors of 24 and 100 are 1, 2 and 4
Common factors of 34 and 100 are: 1 and 2.
The common factors of 75 and 100 are 1, 5 and 25.
The common factors are: 1, 5
The common factors are: 1, 5
The common factors are: 1, 5
The common factors are: 1, 5.
1 and 5 are their only common factors.
Any of the factors 1 through 200 can be common.