Solution: The GCF of 28 and 149 is 1MethodsHow to find the GCF of 28 and 149 using Prime FactorizationOne way to find the GCF of 28 and 149 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 149?Here is the prime factorization of 28:22×712^2 × 7^122×71And this is the prime factorization of 149:1491149^11491When you compare the prime factorization of these two numbers, you can see that there are no matching prime factors. When this is the case, it means that there are no common factors between these two numbers. As a result, the GCF of 28 and 149 is 1.Thus, the GCF of 28 and 149 is: 1How to Find the GCF of 28 and 149 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 28 and 149 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 149:Factors of 28: 1, 2, 4, 7, 14, 28Factors of 149: 1, 149When you compare the two lists of factors, you can see that the only common factor is 1. So, in this case, the GCF of 28 and 149 is 1.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 69 and 81?What is the GCF of 79 and 13?What is the GCF of 17 and 1?What is the GCF of 29 and 96?What is the GCF of 26 and 144?