Solution: The GCF of 143 and 77 is 11MethodsHow to find the GCF of 143 and 77 using Prime FactorizationOne way to find the GCF of 143 and 77 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 143?What are the Factors of 77?Here is the prime factorization of 143:111×13111^1 × 13^1111×131And this is the prime factorization of 77:71×1117^1 × 11^171×111When 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 143 and 77 by multiplying all the matching prime factors to get a GCF of 143 and 77 as 121:Thus, the GCF of 143 and 77 is: 121How to Find the GCF of 143 and 77 by Listing All Common FactorsThe first step to this method of finding the Greatest Common Factor of 143 and 77 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, 143 and 77:Factors of 143: 1, 11, 13, 143Factors of 77: 1, 7, 11, 77When you compare the two lists of factors, you can see that the common factor(s) are 1, 11. Since 11 is the largest of these common factors, the GCF of 143 and 77 would be 11.Find the GCF of Other Number PairsWant more practice? Try some of these other GCF problems:What is the GCF of 46 and 134?What is the GCF of 58 and 25?What is the GCF of 37 and 97?What is the GCF of 63 and 60?What is the GCF of 75 and 106?