Solution: The GCF of 40 and 133 is 1MethodsHow to find the GCF of 40 and 133 using Prime FactorizationOne way to find the GCF of 40 and 133 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 40?What are the Factors of 133?Here is the prime factorization of 40:23×512^3 × 5^123×51And this is the prime factorization of 133:71×1917^1 × 19^171×191When 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 40 and 133 is 1.Thus, the GCF of 40 and 133 is: 1How to Find the GCF of 40 and 133 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 40 and 133 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, 40 and 133:Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40Factors of 133: 1, 7, 19, 133When you compare the two lists of factors, you can see that the only common factor is 1. So, in this case, the GCF of 40 and 133 is 1.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 66 and 30?What is the GCF of 69 and 28?What is the GCF of 145 and 75?What is the GCF of 78 and 116?What is the GCF of 105 and 55?