Judgment: 15 and 16 have no greatest common factor
It's wrong
The greatest common factor of 15 and 16 is 1
39 and 52 greatest common factor
13
What is the greatest common factor of 39 and 52?
The greatest common factor of 39 and 52 is 13
39=3*13
52=4*13
What is the greatest common factor of 39 and 65
13