Solution: The GCF of 69 and 135 is 3
Methods
How to find the GCF of 69 and 135 using Prime Factorization
One way to find the GCF of 69 and 135 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 69?
What are the Factors of 135?
Here is the prime factorization of 69:
3
1
×
2
3
1
3^1 × 23^1
3 1 × 2 3 1
And this is the prime factorization of 135:
3
3
×
5
1
3^3 × 5^1
3 3 × 5 1
When 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 69 and 135 by multiplying all the matching prime factors to get a GCF of 69 and 135 as 9:
Thus, the GCF of 69 and 135 is: 9
How to Find the GCF of 69 and 135 by Listing All Common Factors
The first step to this method of finding the Greatest Common Factor of 69 and 135 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, 69 and 135:
Factors of 69: 1, 3, 23, 69
Factors of 135: 1, 3, 5, 9, 15, 27, 45, 135
When you compare the two lists of factors, you can see that the common factor(s) are 1, 3. Since 3 is the largest of these common factors, the GCF of 69 and 135 would be 3.
Find the GCF of Other Number Pairs
Want more practice? Try some of these other GCF problems:
What is the GCF of 123 and 60?
What is the GCF of 115 and 130?
What is the GCF of 75 and 58?
What is the GCF of 47 and 59?
What is the GCF of 118 and 6?