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# How to find the Greatest Common Factor Worksheet, Examples, and Definition

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How to find Greatest Common Factor in 3 EASY steps (Avoid these common mistakes)

### Key Points about Greatest Common Factor

• The Greatest Common Factor, also known as GCF, is the largest number that divides two or more integers without leaving a remainder.
• It is also known as the greatest common measure, highest common factor, or highest common divisor.
• GCF is a fundamental concept that is taught in elementary and middle school mathematics.

## What is the Greatest Common Factor?

Greatest Common Factor (GCF) is an important concept in mathematics. It is the largest number that divides two or more integers without leaving a remainder. In other words, it is the greatest common divisor of two or more numbers. GCF is used in many mathematical operations, including simplifying fractions, finding common denominators, and solving equations.

In math, the GCF is also known as the greatest common measure, highest common factor, or highest common divisor. It is a fundamental concept that is taught in elementary and middle school mathematics. Understanding GCF is crucial for students to excel in math and solve complex problems.

The Greatest Common Factor is the greatest number that divides into two larger numbers. The Greatest Common Factor, GCF for short, can be found by factoring down each number into prime factors. Once the numbers are into prime factors, you multiply the prime factors together that each number has in common. If there are no common factors, then the Greatest Common Factor is one.

Common Core Standard: 6.NS.4

## What is GCF in math?

In mathematics, the Greatest Common Factor (GCF) of two or more integers is the largest positive integer that divides each of the integers without a remainder.

The GCF is also known as the Greatest Common Divisor (GCD) or Highest Common Factor (HCF). It is a fundamental concept in number theory and is used in many mathematical operations.

To find the GCF of two or more numbers, one can list down all the factors of each number and find the largest factor that is common to all the numbers. Alternatively, one can use the Euclidean algorithm, which is a faster and more efficient method.

The GCF is often used in simplifying fractions, finding common denominators, and solving equations in algebra. It is also used in cryptography to generate public and private keys for secure communication.

Overall, the GCF is an important concept in mathematics that has many practical applications in various fields.

## Greatest Common Factor Definition

The Greatest Common Factor (GCF) is the largest positive integer that divides two or more numbers without leaving a remainder. It is also known as the Highest Common Factor (HCF). The GCF is used to simplify fractions and find common denominators.

To find the GCF of two or more numbers, one can list all the factors of each number and find the largest factor that is common to all the numbers. Alternatively, one can use the prime factorization of the numbers to find the GCF.

For example, the GCF of 12 and 18 is 6 because 6 is the largest factor that divides both 12 and 18 without leaving a remainder. The prime factorization of 12 is 2 x 2 x 3 and the prime factorization of 18 is 2 x 3 x 3. The common factors are 2 and 3, and the largest common factor is 2 x 3 = 6.

The GCF can be calculated for any set of numbers, including negative numbers, natural numbers, whole numbers, and integers. If one or more of the numbers is negative, the GCF is still positive.

The GCF is also used in the Euclidean algorithm, which is a method to find the GCF of two numbers. The algorithm involves dividing the larger number by the smaller number and finding the remainder. The larger number is then replaced by the smaller number and the remainder, and the process is repeated until the remainder is zero. The GCF is the last nonzero remainder.

In summary, the Greatest Common Factor is the largest positive integer that divides two or more numbers without leaving a remainder. It can be found by listing the factors or using the prime factorization of the numbers. The GCF can be calculated for any set of numbers, including negative numbers, and is used to simplify fractions and find common denominators.

## GCF Meaning

Greatest Common Factor (GCF) is a mathematical term used to describe the largest number that divides two or more numbers without leaving any remainder. It is also known as the Highest Common Factor (HCF) or the Greatest Common Divisor (GCD).

The GCF is used to simplify fractions, find common denominators, and solve problems related to factors. It is an essential concept in number theory and is widely used in algebra, geometry, and other branches of mathematics.

To find the GCF of two or more numbers, you need to list all the factors of each number and find the largest factor that is common to all of them. For example, the GCF of 12 and 18 is 6, because the factors of 12 are 1, 2, 3, 4, 6, and 12, and the factors of 18 are 1, 2, 3, 6, 9, and 18. The largest factor that is common to both 12 and 18 is 6.

The GCF is often used to simplify fractions. To simplify a fraction, you need to divide both the numerator and the denominator by their GCF. For example, to simplify the fraction 24/36, you need to find the GCF of 24 and 36, which is 12. Then, you divide both 24 and 36 by 12 to get 2/3.

In summary, the GCF is the largest number that divides two or more numbers without leaving any remainder. It is used to simplify fractions, find common denominators, and solve problems related to factors.

## How to Find GCF of Two Numbers

Finding the Greatest Common Factor (GCF) of two or more numbers is a fundamental concept in mathematics and is used in various mathematical problems. The GCF is the largest number that divides two or more numbers without leaving a remainder.

### Finding GCF of Multiple Numbers

To find the GCF of multiple numbers, you can use either the method of prime factorization or the method of listing the factors. In the method of prime factorization, you find the prime factors of each number and then find the common factors. The product of the common factors is the GCF. In the method of listing the factors, you list all the factors of each number and then find the common factors. The largest common factor is the GCF.

For example, to find the GCF of 12, 18, and 24, you can use the method of prime factorization. The prime factors of 12 are 2 and 3, the prime factors of 18 are 2 and 3, and the prime factors of 24 are 2, 2, 2, and 3. The common factors are 2 and 3. The product of the common factors is 6, which is the GCF.

### GCF and LCM Relationship

The GCF and the Least Common Multiple (LCM) of two or more numbers are related. The LCM is the smallest number that is a multiple of two or more numbers. The relationship between the GCF and the LCM is given by the formula:

GCF × LCM = Product of the Numbers

For example, the GCF of 12 and 18 is 6, and the LCM of 12 and 18 is 36. The product of 12 and 18 is 216. The relationship between the GCF and the LCM is:

6 × 36 = 216

Therefore, the GCF and the LCM are related by the product of the numbers.

In summary, the GCF is the largest common factor of two or more numbers, and it can be found using the method of prime factorization or the method of listing the factors. The GCF and the LCM are related by the product of the numbers. The concept of GCF is used in various mathematical problems, such as finding the ratio of two fractions, simplifying polynomials, and solving problems related to circles.

## 4 Easy Greatest Common Factor Examples

The greatest common factor (GCF) is the largest positive integer that divides two or more numbers without leaving a remainder. Here are a few examples of how to find the GCF of different numbers.

### Example 1: Finding the GCF of 12 and 20

To find the GCF of 12 and 20, you first need to list the factors of each number. The factors of 12 are 1, 2, 3, 4, 6, and 12. The factors of 20 are 1, 2, 4, 5, 10, and 20. The common factors of 12 and 20 are 1, 2, and 4. The largest common factor is 4. Therefore, the GCF of 12 and 20 is 4.

### Example 2: Using a GCF Calculator

If you have trouble finding the GCF manually, you can use a GCF calculator. Simply enter the numbers you want to find the GCF of, and the calculator will give you the answer. This is a quick and easy way to find the GCF of large numbers.

### Example 3: Simplifying Fractions

One practical use of the GCF is to simplify fractions. To simplify a fraction, you divide both the numerator and denominator by their GCF. For example, to simplify the fraction 12/20, you first find the GCF of 12 and 20, which is 4. Then you divide both the numerator and denominator by 4 to get 3/5.

### Example 4: Finding the GCF of Three or More Numbers

To find the GCF of three or more numbers, you can use the same method as for two numbers. First, list the factors of each number. Then, identify the common factors and choose the largest one. For example, to find the GCF of 12, 20, and 5, you list the factors of each number: 1, 2, 3, 4, 6, and 12 for 12; 1, 2, 4, 5, 10, and 20 for 20; and 1 and 5 for 5. The common factors are 1 and 5, and the largest common factor is 5. Therefore, the GCF of 12, 20, and 5 is 5.

In conclusion, the GCF is an important concept in mathematics that is used to simplify fractions, find common denominators, and more. By using the method of listing factors and identifying common factors, you can easily find the GCF of two or more numbers.

## More GCF Examples

To further illustrate how to find the greatest common factor (GCF) of a set of numbers, here are some additional examples:

### Example 1

Find the GCF of 24 and 36.

First, list the factors of each number:

• Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
• Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36

Then, identify the common factors: 1, 2, 3, 4, 6, and 12.

Since 12 is the largest common factor, the GCF of 24 and 36 is 12.

### Example 2

Find the GCF of 60 and 84.

First, list the factors of each number:

• Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
• Factors of 84: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84

Then, identify the common factors: 1, 2, 3, 4, 6, and 12.

Since 12 is the largest common factor, the GCF of 60 and 84 is 12.

### Example 3

Find the GCF of 48, 64, and 80.

First, list the factors of each number:

• Factors of 48: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48
• Factors of 64: 1, 2, 4, 8, 16, 32, 64
• Factors of 80: 1, 2, 4, 5, 8, 10, 16, 20, 40, 80

Then, identify the common factors: 1, 2, 4, 8.

Since 8 is the largest common factor, the GCF of 48, 64, and 80 is 8.

By following the steps of listing the factors and identifying the common factors, one can easily find the GCF of any set of numbers.

## 5 Quick Greatest Common Factor Practice Problems

/5

Greatest Common Factor Quiz

Click Start to begin the practice quiz!

1 / 5

Find the Greatest Common Factor.

25 and 80

2 / 5

Find the Greatest Common Factor.

12 and 40

3 / 5

Find the Greatest Common Factor.

48 and 80

4 / 5

Find the Greatest Common Factor.

56 and 20

5 / 5

Find the Greatest Common Factor.

50 and 20

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### How to find the GCF of 2 numbers?

To find the Greatest Common Factor (GCF) of two numbers, you need to list the factors of each number and then identify the largest factor that is common to both numbers. One way to do this is to use the prime factorization method, where you break down both numbers into their prime factors and then multiply the common prime factors.

### What is the GCF used for in mathematics?

The GCF is a useful tool in mathematics, particularly in the areas of fractions, ratios, and simplifying expressions. For example, when adding or subtracting fractions, you need to find a common denominator, which is often the least common multiple (LCM) of the denominators, and to do that, you need to find the GCF of the denominators.

### Can the GCF of two numbers be greater than the smaller number?

Yes, the GCF of two numbers can be greater than the smaller number. In fact, the GCF can be as large as the smaller number itself, if the two numbers are equal. For example, the GCF of 12 and 12 is 12.

### What is the process for finding the GCF of more than two numbers?

To find the GCF of more than two numbers, you can use either the prime factorization method or the division method. In the prime factorization method, you break down each number into its prime factors and then multiply the common prime factors. In the division method, you divide the largest number by the smallest number and then divide the remainder by the smaller number, repeating this process until there is no remainder.

### What is the relationship between prime factorization and finding the GCF?

The prime factorization method is a reliable way to find the GCF because it breaks down each number into its prime factors, which are the building blocks of all numbers. By multiplying the common prime factors, you can find the largest factor that is common to both numbers.

### Are there any real-life applications for knowing how to find the GCF?

Yes, there are several real-life applications of the GCF, such as in baking, where you need to measure ingredients in common fractions and simplify them to get accurate measurements. The GCF is also used in music theory, where it is used to find the time signature of a piece of music.

### What does Greatest Common Factor mean?

The Greatest Common Factor (GCF) is the largest factor that is common to two or more numbers. It is also known as the Greatest Common Divisor (GCD) or the Highest Common Factor (HCF). The GCF is used to simplify fractions, find common denominators, and solve problems involving ratios and proportions.

## Greatest Common Factor Worksheet Video Explanation

Watch our free video on how to find GCF. This video shows how to solve problems that are on our free Greatest Common Factor worksheet that you can get by submitting your email above.

Watch the free Greatest Common Factor video on YouTube here: Greatest Common Factor Video

Video Transcript:

This video is about how to find the greatest common factor. You can get the gcf worksheet used in this video for free by clicking on the link in the description below.

The greatest common factor definition in math is the largest common factor that goes into two separate numbers. Now factors are just numbers that you can multiply together to make another number. For example, if we were to take a number like the number 12 and we were to break it down into factors that were prime numbers only, this would be called prime factorization. We’re going to factor 12 into a list of prime factors that when multiplied together will equal 12.

The first prime factor I’m going to factor out of this 12 is 2 and I’m using 2 because it’s an even number and I know that 2 will have to go into 12 because it’s even. Now we have to figure out 2 times what is 12, 2 times 6 is 12. We cannot break 2 down anymore because it’s a prime factor nothing else goes into it except itself and the number 1. But we can break 6 down into prime factors. I can break 6 down into 2 times 3 and now we have a list of prime factors because each number is a prime number. 2 and 3 are all prime which means that we are done with our factorization. You could say 12 broken down into prime factorization is going to be 2 times 2 times 3 and I’m going to write it like this 2 times 2 times 3 and this is what we’re going to use to figure out the greatest common factor.

If we were given a greatest common factor example like finding the greatest common factors between 50 and 20, what we could do is we could take each number and break it down into a list of prime factorization. You could do this a couple different ways. I’m going to use the factor tree method that I just showed you. The first number I’m going to do is I’m going to take the number 50 and I’m going to break it down into prime factors. Now 50 is an even number so I know that 2 automatically has to go into 50. 2 times 25 is 50. Then if I look 25 can be broken down again into prime factors and 25 in the prime factors is going to be 5 times 5. Now I have my list of prime factors which in this case is 2 times 5 times 5. I can do the same thing for the number 20. I’m going to break down 20. 20 is an even number so I’m going to break it down by 2 and then 2 times 10 is 20 and then I can break 10 down again into 2 times 5. Now I know that I’m done because it’s only prime numbers that I have left over.

Now i’m going to take 50 and 20 and I’m going to list them both out by their list of prime factors 50 is 2 times 5 times 5 and 20 is 2 times 2 times 5. In order to find the greatest common factor, you’re going to take the pairs of prime factors that both 50 and 20 have in common. I’m going to use this first pair of twos and I’m going to say greatest common factor. We’re going to say 2 because we have 2’sM we have a pair of 2’s then I’m going to use this pair of 5’s here and I’m going to have 2 times 5. Now the extra 5 this 5 and this 2 do not get used because they don’t have a pair from the other number. If I had an extra let’s say I had an extra 2 up here then I could use this 2 from 20 and this 2 but because I don’t have that extra pair, I can’t use them. I can only use the numbers that have a pair from both. Now our greatest common factor is going to be 2 times 5 which is 10. The solution to the greatest common factor between 50 and 20 is the number 10. Let’s do a couple practice problems from our greatest common factor worksheet.

Number one on our gcf worksheets gives us the numbers 12 and 40 and asks us to find the highest common factor between them. What I’m going to do is I’m going to take the number 12 and the number 40 and I’m going to break them down using prime factorization. 12 is even so I’m going to use the number 2. I’m going to start with the number 2 and 2 times 6 is going to be 12. 2 is a prime number but 6 is not. Now I can break 6 down into 2 times 3 and then for 40. 40 is an even number. I’m going to use 2. 2 times 20 is 40. 20 again is an even number so I’m going to use 2 again, this would be 2 times 10. 10 is an even number and I’m going to say 2 and then 2 times 5 is 10. Now I have my prime factorization. All of these are prime so I know it’s been factored correctly. Now what I’m going to do is I’m going to list out my numbers 12 and 40 into prime factorization. 12 was 2 times 2 times 3 and 40 was 2 times 2 times 2 times 5. Then we can grab the pairs of numbers that are in both 12 and 40. If we look, we have a pair of twos the very first numbers or pair of two. We’re going to use those and then we also have a second pair of twos here. We’re going to use those and then we have for the number 12 we have a 3 but 40 does not have a 3. We can’t use this 3. 40 has another 2 but 12 does not have a 2 to go with it so we can’t use that 2 and then for the 5 and 40 we can’t use it because 12 does not have a 5. Our greatest common factor is going to be the pairs of numbers that we can multiply together. We have a two this prime factor of two times the other two the other prime factor of two. Our greatest common factor is going to be two times two which is four and four is going to be our greatest common factor between 12 and 40.

The next problem we’re going to show you on our greatest common factor worksheets for teaching you how to find the highest common factor is number four. This gives us 32 and 28 as the numbers that we need to find the greatest common factor of. The first thing I’m going to do is I’m going to factor this out using the prime factorization methods. 32 is an even number so I’m going to break it down into 2 times 16. 16 is an even number so I’m going to say 2 times 8. 8 is an even number so I’m going to say 2 times 4 and then 4 can be broken down into 2 times 2. 28 is also an even number so I’m going to say 2 times 14 and then 14 I’m going to say 2 times 7.  Now we have our numbers listed out in prime factors and I’m going to circle them here. I’m going to take 32 and I’m going to list it by its greatest common factors which are going to be in this case 32 is 2 times 2 times 2 times 2 times 2, five twos and then 28 when I list 28 out it’s going to be 2 times 2 times 7. To find the greatest common factor we’re going to take our list of prime factors that both numbers share. In other words you could say the pairs of prime factors. Our first pair is going to be this first two. We’re going to say two then our second pair we have another set of twos. Another pair of twos and then if we look 32 has a bunch of twos. Two, two, two, but 28 doesn’t have any more twos so we can’t use those twos. 28 has a seven. Seven is not in 32 so we can’t use that 7 either. Our greatest common factor is going to be 2 times 2 which means that the greatest common factor between 32 and 28 is 4. Hopefully you found this video helpful for teaching you how to find the gcf. Try all the practice problems by downloading the free greatest common factor worksheets above.