Are you on the hunt for the GCF of 16 and 20? Since you're on this page I'd guess so! In this quick guide, we'll walk you through how to calculate the greatest common factor for any numbers you need to check. Let's jump in!
Want to quickly learn or show students how to find the GCF of two or more numbers? Play this very quick and fun video now!
First off, if you're in a rush, here's the answer to the question "what is the GCF of 16 and 20?":
GCF of 16 and 20 = 4
What is the Greatest Common Factor?
Put simply, the GCF of a set of whole numbers is the largest positive integer (i.e whole number and not a decimal) that divides evenly into all of the numbers in the set. It's also commonly known as:
- Greatest Common Denominator (GCD)
- Highest Common Factor (HCF)
- Greatest Common Divisor (GCD)
There are a number of different ways to calculate the GCF of a set of numbers depending how many numbers you have and how large they are.
For smaller numbers you can simply look at the factors or multiples for each number and find the greatest common multiple of them.
For 16 and 20 those factors look like this:
- Factors for 16: 1, 2, 4, 8, and 16
- Factors for 20: 1, 2, 4, 5, 10, and 20
As you can see when you list out the factors of each number, 4 is the greatest number that 16 and 20 divides into.
Prime Factors
As the numbers get larger, or you want to compare multiple numbers at the same time to find the GCF, you can see how listing out all of the factors would become too much. To fix this, you can use prime factors.
List out all of the prime factors for each number:
- Prime Factors for 16: 2, 2, 2, and 2
- Prime Factors for 20: 2, 2, and 5
Now that we have the list of prime factors, we need to find any which are common for each number.
Looking at the occurences of common prime factors in 16 and 20 we can see that the commonly occuring prime factors are 2 and 2.
To calculate the prime factor, we multiply these numbers together:
GCF = 2 x 2 = 4
Find the GCF Using Euclid's Algorithm
The final method for calculating the GCF of 16 and 20 is to use Euclid's algorithm. This is a more complicated way of calculating the greatest common factor and is really only used by GCD calculators.
If you want to learn more about the algorithm and perhaps try it yourself, take a look at the Wikipedia page.
Hopefully you've learned a little math today and understand how to calculate the GCD of numbers. Grab a pencil and paper and give it a try for yourself. (or just use our GCD calculator - we won't tell anyone!)
Cite, Link, or Reference This Page
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<a href="//visualfractions.com/calculator/greatest-common-factor/gcf-of-16-and-20/">Greatest Common Factor of 16 and 20</a>
"Greatest Common Factor of 16 and 20". VisualFractions.com. Accessed on October 29, 2022. //visualfractions.com/calculator/greatest-common-factor/gcf-of-16-and-20/.
"Greatest Common Factor of 16 and 20". VisualFractions.com, //visualfractions.com/calculator/greatest-common-factor/gcf-of-16-and-20/. Accessed 29 October, 2022.
Greatest Common Factor of 16 and 20. VisualFractions.com. Retrieved from //visualfractions.com/calculator/greatest-common-factor/gcf-of-16-and-20/.
The first step to this method of finding the Greatest Common Factor of 20 and 16 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 16:
Factors of 20: 1, 2, 4, 5, 10, 20
Factors of 16: 1, 2, 4, 8, 16
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 20 and 16 would be 4.
The GCF of 16 and 20 is 4.
Steps to find GCF
- Find the prime factorization of 16
16 = 2 × 2 × 2 × 2 - Find the prime factorization of 20
20 = 2 × 2 × 5 - To find the GCF, multiply all the prime factors common to both numbers:
Therefore, GCF = 2 × 2
- GCF = 4
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GCF Calculator
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The greatest common factor (GCF) is also known as greatest common divisor (GCD) or highest common factor (HCF).