There cannot be a greatest common factor (GCF) of just one number. To be common there need to be at least two numbers. If you find all the factors of two or more numbers, and you find some factors are the same ("common"), then the largest of those common factors is the Greatest Common Factor.
Chat with our AI personalities
What is the Greatest common factor of 21 and 84
the greatest common factor is 10
It is: 10
The GCF is 7.
The GCF is 3.