Solution: The GCF of 42 and 121 is 1
Methods
How to find the GCF of 42 and 121 using Prime Factorization
One way to find the GCF of 42 and 121 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 42?
What are the Factors of 121?
Here is the prime factorization of 42:
2
1
×
3
1
×
7
1
2^1 × 3^1 × 7^1
2 1 × 3 1 × 7 1
And this is the prime factorization of 121:
1
1
2
11^2
1 1 2
When 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 42 and 121 is 1.
Thus, the GCF of 42 and 121 is: 1
How to Find the GCF of 42 and 121 by Listing All Common Factors
The first step to this method of finding the Greatest Common Factor of 42 and 121 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, 42 and 121:
Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 121: 1, 11, 121
When you compare the two lists of factors, you can see that the only common factor is 1. So, in this case, the GCF of 42 and 121 is 1.
Find the GCF of Other Number Pairs
Want more practice? Try some of these other GCF problems:
What is the GCF of 15 and 117?
What is the GCF of 100 and 58?
What is the GCF of 101 and 71?
What is the GCF of 28 and 2?
What is the GCF of 49 and 126?