Solution: The GCF of 28 and 119 is 7MethodsHow to find the GCF of 28 and 119 using Prime FactorizationOne way to find the GCF of 28 and 119 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 28?What are the Factors of 119?Here is the prime factorization of 28:22×712^2 × 7^122×71And this is the prime factorization of 119:71×1717^1 × 17^171×171When 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 28 and 119 by multiplying all the matching prime factors to get a GCF of 28 and 119 as 49:Thus, the GCF of 28 and 119 is: 49How to Find the GCF of 28 and 119 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 28 and 119 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, 28 and 119:Factors of 28: 1, 2, 4, 7, 14, 28Factors of 119: 1, 7, 17, 119When you compare the two lists of factors, you can see that the common factor(s) are 1, 7. Since 7 is the largest of these common factors, the GCF of 28 and 119 would be 7.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 108 and 99?What is the GCF of 145 and 49?What is the GCF of 107 and 135?What is the GCF of 69 and 46?What is the GCF of 118 and 21?