What is the greatest common factor of 15 and 31?

The greatest common factor of 15 and 31 is 1.

Step-by-step explanation:

What are the factors of 15?

1, 15 and 3, 5

What are the factors of 31?

31 and 1

We can see that 31 and 15 only share on common factor, which is 1.

1 is the greatest and the only factor!

GCF - 1

Step-by-step explanation:

15 - 1, 3, 15

31 - 1, 31

31 is a prime number so the only factors of it are 1 and itself. Therefore, the answer has to be 1.

GCF = 1

Hope this helps! :)