Natural numbers

Question

The common factors of two numbers are 1,5 and 7. Find the greatest number by which the two numbers can be divided without leaving any remainder?

Answer 1

One number might be 5•7•A and the other might be 5•7•B, where A and B are different positive integers not having 5 or 7 as a factor.  Looks like both numbers are divisible ('evenly') by 35.

 

BTW: mentioning 1 as a common factor is an unimportant statement.