Just 1.
They all have factors of 1 and 5 in common
Since 100 is a factor of 200, all of its factors are common.
The common factors are: 1, 5, 25.
The common factors are: 1, 2, 5, 10, 25, 50.
Well, honey, the common factors of 100 and 225 are 1, 5, and 25. That's all there is to it. No need to make it more complicated than it needs to be.
1, 5 and 25
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.