Solution: The GCF of 20 and 69 is 1
Methods
How to find the GCF of 20 and 69 using Prime Factorization
One way to find the GCF of 20 and 69 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 20?
What are the Factors of 69?
Here is the prime factorization of 20:
2
2
×
5
1
2^2 × 5^1
2 2 × 5 1
And this is the prime factorization of 69:
3
1
×
2
3
1
3^1 × 23^1
3 1 × 2 3 1
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 20 and 69 is 1.
Thus, the GCF of 20 and 69 is: 1
How to Find the GCF of 20 and 69 by Listing All Common Factors
The first step to this method of finding the Greatest Common Factor of 20 and 69 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, 20 and 69:
Factors of 20: 1, 2, 4, 5, 10, 20
Factors of 69: 1, 3, 23, 69
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 20 and 69 is 1.
Find the GCF of Other Number Pairs
Want more practice? Try some of these other GCF problems:
What is the GCF of 48 and 121?
What is the GCF of 130 and 46?
What is the GCF of 120 and 101?
What is the GCF of 53 and 84?
What is the GCF of 43 and 47?