Solution: The GCF of 55 and 150 is 5MethodsHow to find the GCF of 55 and 150 using Prime FactorizationOne way to find the GCF of 55 and 150 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 55?What are the Factors of 150?Here is the prime factorization of 55:51×1115^1 × 11^151×111And this is the prime factorization of 150:21×31×522^1 × 3^1 × 5^221×31×52When 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 55 and 150 by multiplying all the matching prime factors to get a GCF of 55 and 150 as 25:Thus, the GCF of 55 and 150 is: 25How to Find the GCF of 55 and 150 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 55 and 150 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, 55 and 150:Factors of 55: 1, 5, 11, 55Factors of 150: 1, 2, 3, 5, 6, 10, 15, 25, 30, 50, 75, 150When you compare the two lists of factors, you can see that the common factor(s) are 1, 5. Since 5 is the largest of these common factors, the GCF of 55 and 150 would be 5.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 123 and 94?What is the GCF of 102 and 130?What is the GCF of 8 and 4?What is the GCF of 114 and 5?What is the GCF of 3 and 25?