One way to find the GCF of 111 and 9 is to compare the prime factorization of each number. To find the prime factorization, you can follow the instructions for each number here:
Here is the prime factorization of 111:
And this is the prime factorization of 9:
When you compare the prime factorization of these two numbers, you can see that there are matching prime factors. You can now find the Greatest Common Factor of 111 and 9 by multiplying all the matching prime factors to get a GCF of 111 and 9 as 9:
Thus, the GCF of 111 and 9 is: 9