# How do you find the GCF of 21, 45?

##### 1 Answer

GCF of 21 and 45 is 3

#### Explanation:

Consider that

Since

Since both 45 and 21 are divisible by 3 it is a common factor. Also, since 3 is the only common factor between the two numbers in their prime factorization; it is the greatest common factor of 45 and 21.

Or GCF (21,45)=3.

Another method

Since

Then we can say

Since 3 is prime GCF (21,45)=3