common divisor
common factor
common measure

There must be some one common factor, something we all did.

The only common factor between everything you do is yourself.

"There must be a common factor among these children," she said.

Are these not common factors between science and the arts?

Like the previous case 2 is not a common factor.

The reason we can't find any common factors among the victims, for example.

"I can give you two common factors right now," David said.

There must be common factors, things which link all three.

Instead, the most common factor was serious mental health problems.

I'd always believed there had to be a common factor involved.