Solution: The GCF of 20 and 150 is 10
Methods
How to find the GCF of 20 and 150 using Prime Factorization
One way to find the GCF of 20 and 150 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 150?
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 150:
2
1
×
3
1
×
5
2
2^1 × 3^1 × 5^2
2 1 × 3 1 × 5 2
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 20 and 150 by multiplying all the matching prime factors to get a GCF of 20 and 150 as 100:
Thus, the GCF of 20 and 150 is: 100
How to Find the GCF of 20 and 150 by Listing All Common Factors
The first step to this method of finding the Greatest Common Factor of 20 and 150 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 150:
Factors of 20: 1, 2, 4, 5, 10, 20
Factors of 150: 1, 2, 3, 5, 6, 10, 15, 25, 30, 50, 75, 150
When you compare the two lists of factors, you can see that the common factor(s) are 1, 2, 5, 10. Since 10 is the largest of these common factors, the GCF of 20 and 150 would be 10.
Find the GCF of Other Number Pairs
Want more practice? Try some of these other GCF problems:
What is the GCF of 51 and 64?
What is the GCF of 110 and 93?
What is the GCF of 88 and 91?
What is the GCF of 44 and 58?
What is the GCF of 114 and 40?