What is the GCF of 8 and 9?
GCF (Greatest Common Factor) of two numbers is the largest possible number which divides the two numbers exactly without any remainder.
Answer: GCF of 8 and 9 is 1
Let us see how to find the GCF of 8 and 9
Explanation:

GCF of 8 and 9 by Prime Factorization
Represent 8 and 9 as a product of its prime factors.
Prime factorization of 8 is 2 × 2 × 2
Prime factorization of 9 is 3 × 3
We don't have any common factors for 8 and 9 . the universal factor1 is the GCF of 8 and 9.

GCF of 8 and 9 by Listing the Common Factors
The factors of 8 and 9 are given below.
Factors of 8: 1, 2, 4, 8
Factors of 9: 1, 3, 9
1 is the only common factor of 8 and 9
So, GCF of 8 and 9 is 1
Since GCF(8, 9) is 1, they are coprime numbers.
You can find the GCF in any of the above methods but the solution will be the same.