What is the greatest common factor of 80 and 90?

Answer 1

The greatest common factor of 80 and 90 is 10. The GCF must be 10. It cannot be more because the difference of the two numbers is 10. Coincidentally, 10 goes into both numbers.

The greatest common factor (GCF) is often also called the greatest common divisor (GCD) or highest common factor (HCF). Keep in mind that these different terms all refer to the same thing: the largest integer which evenly divides two or more numbers.