Solution: The GCF of 63 and 135 is 9MethodsHow to find the GCF of 63 and 135 using Prime FactorizationOne way to find the GCF of 63 and 135 is to compare the prime factorization of each number. To find the prime factorization, you can follow the instructions for each number here:What are the Factors of 63?What are the Factors of 135?Here is the prime factorization of 63:32×713^2 × 7^132×71And this is the prime factorization of 135:33×513^3 × 5^133×51When 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 63 and 135 by multiplying all the matching prime factors to get a GCF of 63 and 135 as 9:Thus, the GCF of 63 and 135 is: 9How to Find the GCF of 63 and 135 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 63 and 135 is to find and list all the factors of each number. Again, you can see how this is done by looking at the “Factors of” articles that are linked to above.Let’s take a look at the factors for each of these numbers, 63 and 135:Factors of 63: 1, 3, 7, 9, 21, 63Factors of 135: 1, 3, 5, 9, 15, 27, 45, 135When you compare the two lists of factors, you can see that the common factor(s) are 1, 3, 9. Since 9 is the largest of these common factors, the GCF of 63 and 135 would be 9.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 87 and 86?What is the GCF of 104 and 10?What is the GCF of 41 and 133?What is the GCF of 120 and 103?What is the GCF of 59 and 15?