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Greatest Common Factor

Last Updated : 06 Nov, 2023
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Greatest Common Factor or GCF is the largest positive integer that evenly divides two or more integers without leaving a residual. In simple words, the Greatest Common Factor is the largest value that can be used to divide these numbers and get whole numbers. 

The biggest positive divisor that all of the provided numbers share, or a common denominator that reduces these numbers to their most basic form, is another method to define the greatest common factor. Greatest Common Factor is a fundamental idea in mathematics and is essential for equation solving, simplifying fractions, and finding common components in a variety of mathematical settings.

In this article, we will discuss the concept of the Greatest Common Factor in detail including definition, methods to find the Greatest Common Factor, and various solved examples for the calculation of the Greatest Common Factor

Greatest-Common-Factors

What is Greatest Common Factor?

The largest number that divides two or more integers without leaving a remainder is known as the Greatest Common Factor (GCF) and it is also referred to as the Greatest Common Divisor (GCD) or Highest Common Factor (HCF). The GCF is essential for reducing difficult mathematical statements and has applications in number theory, cryptography, and computer science.

Greatest Common Factor Definition

The Greatest Common Factor (GCF) is the greatest positive integer that evenly divides two or more integers without leaving a remainder.

Greatest Common Factor is a fundamental mathematical idea used to simplify fractions and solve algebraic problems. One approach for determining the GCF is prime factorization, which involves identifying the prime factors of each integer and multiplying the common factors with the largest exponent together. The Euclidean algorithm, which includes consecutive division until the remainder reaches zero, is another option.

How to Find the Greatest Common Factor?

The two methods for determining the biggest common factor between two integers are as follows:

Greatest Common Factor by Listing Out Common Factors

This technique is methodically noting and contrasting the components of two or more integers in order to get the Greatest Common Factor (GCF). To divide all the supplied numbers without leaving a remainder, the factors of each number are determined and then compared to get the greatest positive integer. For small or relatively simple groups of integers, this method offers a simple technique to identify the largest common divisor that the numbers share.

Let’s determine the two numbers 48 and 60’s greatest common factor (GCF) by systematically listing each of their common factors.

Step 1: Write down each number’s components in order.

  • Factors of 48: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48
  • Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60

Step 2: Find the elements that both numbers have in common.

  • Common factors: 1, 2, 3, 4, 6, 12

Step 3: Determine the largest common factor.

  • The largest common factor is 12.

The greatest common factor (GCF) between 48 and 60 is 12.

In this case, we enumerated the factors of both numbers, located the ones that they have in common, and discovered that the biggest one is 12. By methodically listing each pair of numbers’ elements and finding the shared factors, it is possible to use this approach to get the GCF of any two numbers.

Greatest Common Factor by Prime Factorization

The GCF of two or more integers is calculated using this approach by first locating their prime factorizations. The numbers are divided into their prime components, and the most prevalent prime components with the smallest exponents are then determined. The GCF of the given numbers is obtained by adding these frequent prime factors. This method makes use of the inherent qualities of prime numbers to find the biggest common divisor shared by the numbers, which is particularly helpful for bigger numbers.

Let’s use the prime factorization technique to get the GCF of two integers, 84 and 108. the following steps:

Step 1: Determine each number’s prime factors.

  • Prime factorization of 84: 2 x 2 x 3 x 7
  • Prime factorization of 108: 2 x 2 x 3 x 3 x 3

Step 2: List the common prime factors and their exponents with the lowest values.

  • Common prime factors: 2 x 2 x 3

Step 3: Determine the common prime factors’ product.

  • 2 x 2 x 3 = 12

The GCF (Greatest Common Factor) of 84 and 108 is 12, which is the result.

Greatest Common Factor by Division Method

The division method is a mathematical approach that is used to calculate the Greatest Common Factor (GCF) of two or more integers. It entails a methodical procedure of splitting data and determining common components. Starting with the supplied integers, divide them one by one, using the residual of each division as the new divisor. This technique is repeated until a remainder of zero is obtained. The GCF is the divisor at this point.

Step 1: Write down the numbers you want to find the GCF of.

  • For example, let’s find the GCF of 24 and 36:

Step 2: Find the prime factors of each number.

  • Prime factors of 24: 2 x 2 x 2 x 3
  • Prime factors of 36: 2 x 2 x 3 x 3

Step 3: Identify the common prime factors among all the numbers.

  • Common prime factor of 24 = 23 * 3
  • Common prime factor of 36 = 22 * 32

Step 4: Take the lowest exponent for each common prime factor. If a prime factor doesn’t appear in all the numbers, it’s not considered.

  • Common factors: 22 and 3

Step 5: Multiply all the common prime factors using the lowest exponent found in step 4.

  • GCF = 22 * 3 = 12.

After finding the Greatest Common Factor (GCF) using the division method, it’s essential to apply the result appropriately. The GCF is an important component in simplifying fractions, calculating equations, and dealing with various mathematical issues, streamlining complicated computations.

Also, learn about Factorization of Polynomials.

Examples of Greatest Common Factor

There are various examples we can consider for calculation of Greatest Common Factor. Let’s consider the following examples.

Greatest Common Factor of 12 and 18

Let’s find the GCF of 12 and 18.

  • Factors of 12 = 1, 2, 3, 4, 6, 12
  • Factors of 18 = 1, 2, 3, 6, 9, 18

Between 12 and 18, 6 is the greatest common number. Considering that all number factors may be found between 1 and 6. The number 6 is by far the larger of these two numbers. Thus, these integers have a GCF of 6.

Greatest Common Factor of 24 and 40

The numbers 24 and 40 are provided. We’ll determine each of these numbers’ components.

  • Factors of 24 = 1, 2, 3, 4, 6, 8, 12, 24
  • Factors of 40 = 1, 2, 4, 5, 8, 10, 20, 40

In this case, the common factors for the numbers 24 and 40 are 1, 2, 4, and 8. The greatest common factor among all of these is 8, hence GCF(24 and 40) = 8.

Greatest Common Factor of 15 and 20

  • Prime factors of 15: 1, 3, 5, 15
  • Prime factors of 20: 1, 2, 4, 5, 10, 20

In this case, the common factors for the numbers 15 and 20 are 1 and 5. The greatest common factor among all of these is 5, hence GCF(15 and 20) = 5.

Greatest Common Factor of Monomial

The highest word that divides two or more monomials without remainder is the greatest common factor (GCF). Finding the biggest word that splits equally into two or more monomials is the Greatest Common Factor (GCF) of monomials.

For example, take the monomials 6x2y and 8xy3:

Step 1: Determine the prime factors of each coefficient and variable term .

  • The prime factors for 6x2y are 2, 3, x2, and y.
  • The prime factors for 8xy3 are 2, 2, 2, x, y3.

Step 2: Find the common factors. The common factors in this situation are 2, x, and y.

Step 3: Find the exponent with the lowest exponent for each common factor. It’s x1 and y1 in this case.

Step 4: Divide the common components by the lowest exponent: 2xy.

As a result, the GCF of  6x2y and 8xy3 is 2xy. This GCF is essential for simplifying monomial expressions and factoring polynomial expressions.

LCM and GCF

Understanding the concepts of Least Common Multiple (LCM) and Greatest Common Factor (GCF) is essential in mathematics. These two principles are essential in many mathematical procedures and problem solutions. Let’s look at the division method used to determine the GCF and how it helps with fractions and equations.

Aspect

Least Common Multiple (LCM)

Greatest Common Factor (GCF)

Definition

The least positive multiple that two or more numbers have in common. The most positive divisor that two or more integers can share.

Objective

Used in a variety of situations to determine the smallest common multiple. Used in a variety of situations to determine the biggest common divisor.

Calculation

Involves figuring out the usual multiples and choosing the least one. Involves finding frequent divisors and picking the biggest one.

Properties

Always larger than or equal to the provided numbers is the LCM. Always, the GCF is less than or equal to the specified values.

Read More,

Solved Examples of Greatest Common Factor

Example 1: Find the Greatest Common Factor (GCF) of 15, 25 and 35.

Solution:

Factors of 15, 25 and 35 are as follows:

Factors of 15 = 1, 3, 5, 15

Factors of 25 = 1, 5, 25

Factors of 35 = 1, 5, 7, 35

Between 15, 25 and 35, 5 is the greatest common number. Considering that all number factors may be found between 1 and 5. The number 5 is by far the larger of these two numbers. Thus, these integers have a GCF of 5.

Example 2: Using the approach of listing factors, determine the GCF of 8, 16, and 32.

Solution:

The numbers 8, 16, and 32 are provided. We’ll determine each of these numbers’ components.

Factors of 8 = 1, 2, 4, 8

Factors of 16 = 1, 2, 4, 8, 16

Factors of 32 = 1, 2, 4, 8, 16, 32

In this case, the common factors for the numbers 8, 16, and 32 are 1, 2, 4, and 8. The greatest common factor among all of these is 8, hence GCF(8,16,32) = 8.

Example 3: By using the prime factorization technique, determine the GCF for 80, 120, and 160.

Solution:

The numbers 80, 120, and 160 are provided. We will determine how many prime factors each of these integers has.

Factors of 80 = 2 x 2 x 2 x 2 x 5

Factors of 120 = 2 x 2 x 2 x 3 x 5

Factors of 160 = 2 x 2 x 2 x 2 x 2 x 5

GCF of 80, 120 and 160 = 2 x 2 x 2 x 5 = 40

GCF (80,120,160) = 2 x 2 x 2 x 5 as a result. The sum of the common prime factors of these three numbers will result in the GCF of these three numbers. GCF of 80, 120 and 160 hence equals 2 x 2 x 2 x 5 = 40.

Practice Problems on Greatest Common Factor

Problem 1: Find the GCF of 12 and 18.

Problem 2: Calculate the GCD of 24 and 36.

Problem 3: Determine the GCF of 48, 60, and 84.

Problem 4: Find the greatest common factor of 35 and 49.

Problem 5: Compute the GCD of 72 and 90.

Problem 6: What is the GCF of 15 and 25?

Problem 7: Find the GCF of 16, 24, and 32.

Problem 8: Calculate the greatest common factor of 56 and 64.

Problem 9: Determine the GCD of 120 and 150.

Problem 10: Find the GCF of 9, 15, and 21.

Greatest Common Factor – FAQs

1. What is “Greatest Common Factor” (GCF)?

The greatest common factor, or GCF, is the largest number among all the common factors of two or more numbers. The GCF is the biggest number that divides the provided two numbers for any two numbers.

2. What is the mathematical concept of the Greatest Common Factor?

Simplifying fractions, factoring algebraic expressions, resolving equations, and identifying common divisors all depend on the greatest common factor. It’s an essential idea that serves as the foundation for many mathematical operations and simplification methods.

3. What is the greatest common factor of 36 and 48?

The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36.

The factors of 48 are 1, 2, 3, 4, 6, 8, 12, 16, 24, and 48.

The common factors of 36 and 48 are 1, 2, 3, 4, 6, and 12.

As a result, the GCF for 36 and 48 is 12.

4. How does prime factorization relate to the GCF?

A number is expressed as the product of its prime components through the process of prime factorization. Finding the common prime factors with the lowest exponents from the prime factorizations of two or more integers yields the GCF of those numbers.

5. What is the greatest common factor of 54 and 36?

The factors of 54 are 1, 2, 3, 6, 9, 18, 27 and 54. The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36. The common factors of 54 and 36 are 1, 2, 3, 6, 9 and 18. As a result, the GCF for 54 and 36 is 18.

6. Can a GCF exist for negative numbers?

Positive numbers can indeed have a GCF. The method used to determine the GCF for negative integers is the same as it is for positive values. For factorization, the numbers’ absolute values are taken into account, and the GCF is calculated in accordance with this.

7. Is GCF larger than LCM?

The LCM is the smallest common multiple of the supplied numbers that can be divided by both, whereas the GCF is the greatest common factor of the given numbers that can be divided by both. Thus, the LCM of any two numbers is bigger than the GCF of the numbers.

8. How do You Find the Greatest Common Factor?

To find the greatest common factor (GCF) of two or more numbers, list their factors and identify the largest number that divides them all evenly.

9. What is the GCF of 12 and 18?

The greatest common factor (GCF) of 12 and 18 is 6.

10. Is GCD and HCF Same?

Yes, GCD (Greatest Common Divisor) and HCF (Highest Common Factor) refer to the same mathematical concept and can be used interchangeably. They both represent the largest number that divides two or more integers without leaving a remainder.



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