Solution: The GCF of 55 and 143 is 11
Methods
How to find the GCF of 55 and 143 using Prime Factorization
One way to find the GCF of 55 and 143 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 55?
What are the Factors of 143?
Here is the prime factorization of 55:
5
1
×
1
1
1
5^1 × 11^1
5 1 × 1 1 1
And this is the prime factorization of 143:
1
1
1
×
1
3
1
11^1 × 13^1
1 1 1 × 1 3 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 55 and 143 by multiplying all the matching prime factors to get a GCF of 55 and 143 as 121:
Thus, the GCF of 55 and 143 is: 121
How to Find the GCF of 55 and 143 by Listing All Common Factors
The first step to this method of finding the Greatest Common Factor of 55 and 143 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, 55 and 143:
Factors of 55: 1, 5, 11, 55
Factors of 143: 1, 11, 13, 143
When 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 55 and 143 would be 11.
Find the GCF of Other Number Pairs
Want more practice? Try some of these other GCF problems:
What is the GCF of 66 and 123?
What is the GCF of 64 and 146?
What is the GCF of 18 and 58?
What is the GCF of 7 and 67?
What is the GCF of 100 and 60?