Solution: The GCF of 63 and 147 is 21MethodsHow to find the GCF of 63 and 147 using Prime FactorizationOne way to find the GCF of 63 and 147 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 147?Here is the prime factorization of 63:32×713^2 × 7^132×71And this is the prime factorization of 147:31×723^1 × 7^231×72When 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 147 by multiplying all the matching prime factors to get a GCF of 63 and 147 as 441:Thus, the GCF of 63 and 147 is: 441How to Find the GCF of 63 and 147 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 63 and 147 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 147:Factors of 63: 1, 3, 7, 9, 21, 63Factors of 147: 1, 3, 7, 21, 49, 147When you compare the two lists of factors, you can see that the common factor(s) are 1, 3, 7, 21. Since 21 is the largest of these common factors, the GCF of 63 and 147 would be 21.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 37 and 86?What is the GCF of 67 and 85?What is the GCF of 75 and 61?What is the GCF of 118 and 56?What is the GCF of 55 and 133?