Solution: The GCF of 84 and 124 is 4
Methods
How to find the GCF of 84 and 124 using Prime Factorization
One way to find the GCF of 84 and 124 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 84?
What are the Factors of 124?
Here is the prime factorization of 84:
2
2
×
3
1
×
7
1
2^2 × 3^1 × 7^1
2 2 × 3 1 × 7 1
And this is the prime factorization of 124:
2
2
×
3
1
1
2^2 × 31^1
2 2 × 3 1 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 84 and 124 by multiplying all the matching prime factors to get a GCF of 84 and 124 as 4:
Thus, the GCF of 84 and 124 is: 4
How to Find the GCF of 84 and 124 by Listing All Common Factors
The first step to this method of finding the Greatest Common Factor of 84 and 124 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, 84 and 124:
Factors of 84: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
Factors of 124: 1, 2, 4, 31, 62, 124
When you compare the two lists of factors, you can see that the common factor(s) are 1, 2, 4. Since 4 is the largest of these common factors, the GCF of 84 and 124 would be 4.
Find the GCF of Other Number Pairs
Want more practice? Try some of these other GCF problems:
What is the GCF of 14 and 122?
What is the GCF of 48 and 144?
What is the GCF of 141 and 47?
What is the GCF of 3 and 9?
What is the GCF of 62 and 71?