Question

Explain why the greatest common factor of two numbers is sometimes 1

Answer 1

some numbers are prime and don't have any other factors only one and itself

Answer 2

So if you have the numbers 6 and 5
Factors of 5 : 1 , 5
Factors of 6 : 1 ,2 , 3 , 6
The only number that you see repeated in both of the factors is 1, so the greatest COMMON factor is 1.
I hope this helped if you still don't get it, message me and i'll try to explain it again!