What is the GCF of 21 and 63?

1 Answer
Oct 23, 2016

Answer:

#21#

Explanation:

The GCF (greatest common factor) of two numbers is the greatest number which is a factor of both of them.

The factors of #21# are: #1, 3, 7, 21#

The factors of #63# are: #1, 3, 7, 9, 21, 63#

The greatest number which is on both lists is #21#, meaning #21# is the greatest common factor.