# Greatest Common Factor

## How can this tool help you?

Determine the GCF of any set of numbers instantly, with this greatest common factor calculator by CalcoPolis. You can use this tool to help you simplify fractions, solve algebra problems, or divide objects into groups.

We'll also review GCF's definition, applications, and solving methods in this quick and handy guide. Let's begin!

## What Is the Greatest Common Factor?

In simple terms, the Greatest Common Factor (GCF) is the largest number that exactly and evenly divides your given numbers without leaving a remainder.

Another way of defining GCF is it's the highest number that's a factor of two or more given numbers.

Example: For the given numbers 8 and 12, the largest number that divides them both with no remainder left is 4. That means, 4 is the GCF.

Other names for the greatest common factor are as follows:

- Greatest Common Divisor
- Highest Common Factor

## The Applications of the Greatest Common Factor

Calculating the GCF is particularly useful when dealing with fractions.

For example, if you want to simplify a fraction, such as 14/21, it would be handy to know that the greatest common factor of the numerator and denominator is 7.

To continue simplifying, divide both 14 and 21 by 7. You'll get 2 and 3.

Therefore, the fraction 14/21 can be simplified into 2/3.

You can apply the same concept when simplifying ratios and solving algebra problems, too.

Outside the classroom, knowing the greatest common factor is handy when dividing objects or people into exact groups.

## How to Find the Greatest Common Factor (GCF)

Aside from using a GCF calculator, you can also solve for the greatest common factor by hand.

The following are some of the ways to do it:

### Listing Method

In this method, we'll simply list down all the factors of your given numbers. Then, we'll spot the common factors and choose the greatest of them all.

Example: Find the GCF of 20 and 40.

Step 1: List down the factors of each number.

Factors of 20: 1, 2, 4, 5, 10, 20

Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40

Step 2: Identify the common factors.

Common factors: 1, 2, 4, 5, 10, 20

Step 3: Choose the Greatest Common Factor (GCF).

GCF: 20

### Prime Factorization Method

Here, all we have to do is express our given numbers in prime factors. Then, we'll take the common factors to get the GCF.

Example: Find the GCF of 15 and 30.

Prime factors of 15: 3 x 5

Prime factors of 30: 3 x 5 x 2

Common factors: 3 x 5 or 15

Therefore, the GCF is 15.

### Division Method

Here are the steps for the division method of finding the GCF:

Step 1: Divide the bigger number by the smaller number using long division.

Step 2: If you get a remainder equal to 0, this means that the divisor is the GCF.

Step 3: If the remainder isn't 0, copy the divisor and divide it by the remainder. Keep repeating this step until you get 0 as the remainder. The final divisor is the GCF.

Example: Find the GCF of 360 and 198.

Step 1: 360 divided by 198 is 1, and the remainder is 162.

Step 2: 198 divided by 162 is 1, and the remainder is 36.

Step 3: 162 divided by 36 is 4, and the remainder is 18.

Step 4: 36 divided by 18 is 2, and the remainder is 0.

Step 5: Since the remainder is 0, then 18 is the final divisor. 18 is the GCF.

## Wrapping Up

We hope this greatest common factor calculator has helped you learn and solve GCFs quickly and conveniently. For more handy and efficient calculators, visit the math category page..

### Authors

Created by **Lucas Krysiak** on 2022-12-22 18:26:51 | Last review by **Mike Kozminsky** on 2023-01-10 17:14:19