GCF stands for Greatest Common Factor. ... Since 1 is a factor of every number, any two or more numbers have a GCF, because even if the numbers are prime, or if they don't share any prime factors, then the GCF will be 1. If they do share any prime factors, then the GCF will be the product of those shared prime factors.

Can the GCF ever be 1?

It is easily possible to have only 1 as a common factor.

What is it called when the GCF is 1?

If their greatest common factor is 1, then one of the two numbers must be a prime number. Their least common multiple must be the product of the two numbers. For example: 5 and 7 are prime numbers because their only factors are 1 and themselves.