Prime Factorization

Prime factorization is one of the fundamental concepts in arithmetic and number theory. It helps in breaking down a number into a product of its prime numbers. Understanding what is prime factorization and how to find prime factorization is essential for solving many mathematical problems, such as calculating HCF, LCM, simplifying fractions, and working with large numbers in algebra and cryptography.

This guide explains the meaning of prime factorization, discusses the prime factors of a number, explores different prime factorization methods, and demonstrates everything with solved examples.

 

Table of Contents

• Definition: What is Prime Factorization?
• What are Prime Factors?
• How to Find Prime Factorization
• Prime Factorization of a Number (1 to 30)
• Prime Factorization Methods
  • Division Method
  • Factor Tree Method
• Applications of Prime Factorization
• Solved Examples
• Conclusion
• FAQs on Prime Factorization

 

Definition: What is Prime Factorization?

To understand what is prime factorization, we first need to understand the concept of prime numbers. A prime number is a number greater than one that has only two factors: one and itself. Examples of prime numbers include 2, 3, 5, 7, 11, 13, and so on.

Prime factorization is the process of expressing a number as a product of prime numbers. These prime numbers are its prime factors. Each number has a unique prime factorization. For example, the prime factorization of 24 is 2 × 2 × 2 × 3, which can also be written as 2^3 × 3. 

Simply put, if we decompose a number until we can no longer break it down except by using prime numbers, we get the prime factorization of that number.

 

What are Prime Factors?

Prime factorization is the process of expressing a number as a product of prime numbers. These prime numbers are called the prime factors of a number. Every number has a unique prime factorization. 

For example, the prime factorization of 24 is 2 × 2 × 2 × 3, which can also be written as 2^3 × 3. 

In simple terms, if we keep breaking a number down until we can only use prime numbers, we get the prime factorization of that number.

 

How to Find Prime Factorization

When learning how to find prime factorization, it is important to be familiar with the list of prime numbers, such as 2, 3, 5, 7, 11, 13, and so on. Prime factorization can be done using two main methods: the division method and the factor tree method. Both are widely used prime factorisation methods in mathematics.

The goal is to keep dividing the number by prime numbers until we are left with only prime numbers in the factors.

 

Prime Factorization of a Number (1–30)

Here is a clear and easy-to-read table showing the Prime Factorization of a Number for the first few natural numbers:

 

 

Prime Factorization Methods

There are two major ways to find the prime factorization of a number. Each prime factorisation method is systematic and helps in breaking down the number into its smallest components.

 

Division Method

The division method is a step-by-step way to find the prime factorization of a number by dividing it by the smallest prime number. You repeat this process with the resulting quotient until the final quotient is 1.

Here are the steps to follow using the division method:

1. Start by dividing the number by the smallest prime number, which is 2.

2. Keep dividing the result by the same prime number until it no longer divides evenly.

3. Move on to the next smallest prime number (3, 5, 7, etc.) and repeat the process.

4. Stop when the final quotient is 1.

This method works well for students who are comfortable with basic division and are handling small to moderately large numbers.

Example:

Find the prime factorization of 72.

72 ÷ 2 = 36
36 ÷ 2 = 18
18 ÷ 2 = 9
9 ÷ 3 = 3
3 ÷ 3 = 1

So, the prime factors of 72 are 2 × 2 × 2 × 3 × 3, or 2^3 × 3^2.

 

Factor Tree Method

The factor tree method is a visual way to find a number's prime factors. It works by dividing the number into two factors. You keep dividing the composite factors until all the resulting numbers are prime. 

Here are the steps to use the factor tree method:  

1. Write the number at the top of the tree.  

2. Break it into any two factors.  

3. If a factor is not a prime number, split it again into two factors.  

4. Keep going until all the branches end in prime numbers.  

The prime numbers at the end of the branches are the prime factors of the original number.

 

Example:

Find the prime factorization of 90.

Start with 90
Split into 9 × 10
9 = 3 × 3
10 = 2 × 5

So, the prime factors are 2, 3, 3, and 5. The prime factorization of 90 is 2 × 3^2 × 5.

Both the division method and the factor tree method are reliable ways to understand how to find prime factorization. Choosing between them depends on whether you prefer a visual method or a procedural one.

 

Applications of Prime Factorization

Prime factorization is more than just a theoretical concept. It has several real-world and mathematical applications that make it a valuable tool in problem-solving.

• Finding the Highest Common Factor (HCF): To find the HCF of two or more numbers, prime factorization is used to identify common prime factors and select the lowest powers among them.

• Finding the Least Common Multiple (LCM): Prime factorization helps in finding the LCM by choosing the highest powers of all prime factors present in the numbers.

• Simplifying Fractions: Fractions can be simplified by canceling common prime factors from the numerator and the denominator.

• Algebraic Expressions: Many algebraic problems involving factorization and simplification benefit from expressing numbers in their prime factorized form.

• Cryptography: Modern encryption systems like RSA use very large numbers and their prime factorization as the basis for secure data encryption, making prime factorization essential in computer science and security.
  
  

Solved Examples

Let’s go through several examples that show how to find prime factorization using both methods.

Example 1:

Find the prime factorization of 100 using the division method.

100 ÷ 2 = 50
50 ÷ 2 = 25
25 ÷ 5 = 5
5 ÷ 5 = 1

Prime factorization of 100 is 2^2 × 5^2

 

Example 2:

Find the prime factorization of 126 using the factor tree method.

Start with 126
Split into 2 × 63
63 = 3 × 21
21 = 3 × 7

So, 126 = 2 × 3 × 3 × 7 or 2 × 3^2 × 7

 

Example 3:

Find the HCF of 36 and 48 using prime factorization.

36 = 2^2 × 3^2
48 = 2^4 × 3

Common prime factors = 2 and 3
Take the lowest powers: 2^2 and 3^1
HCF = 2^2 × 3 = 12

 

Example 4:

Find the LCM of 30 and 45 using prime factorization.

30 = 2 × 3 × 5
45 = 3^2 × 5

Take all prime factors with highest powers: 2, 3^2, 5
LCM = 2 × 3^2 × 5 = 90

 

Example 5:

Find the prime factorization of 60.

60 ÷ 2 = 30
30 ÷ 2 = 15
15 ÷ 3 = 5
5 ÷ 5 = 1

So, prime factorization of 60 is 2^2 × 3 × 5

 

Conclusion

Prime factorization is a powerful mathematical tool that allows us to break down complex numbers into simpler prime numbers. Whether you use the division method or the factor tree method, knowing how to find prime factorization will make it easier to solve problems involving greatest common factors, least common multiples, and simplification of expressions.

 

Related Links

Prime Factorization of HCF and LCM - Explore how prime factorization helps find the HCF and LCM of numbers easily.

Factors of a Number - Learn how to identify the factors of a number and understand their role in division and multiplication.

HCF - Understand how to find the Highest Common Factor (HCF) of two or more numbers using different methods

 

Frequently Asked Questions On Prime Factorization

1. What is prime factorization explained easily?

Answer: Prime factorization is the process of breaking down a number into a product of prime numbers. A prime number is a number that has only two factors: 1 and itself.
For example, the prime factorization of 30 is:
30 = 2 × 3 × 5
All these numbers (2, 3, and 5) are prime numbers. So, the product of these primes gives back the original number.

 

2. What is the prime factorization of 42?

Answer:
To find the prime factorization of 42, divide by the smallest prime numbers step-by-step:

42 ÷ 2 = 21
21 ÷ 3 = 7
7 ÷ 7 = 1

So, the prime factorization of 42 is:
42 = 2 × 3 × 7

 

3. What is a prime factor of 20?

Answer:
The number 20 can be broken into prime factors:

20 = 2 × 2 × 5
So, the prime factors of 20 are:
2 and 5

Both are prime numbers that divide 20 exactly.

 

4. What is the prime factorization of 144?

Answer:
Let’s find the prime factorization of 144 using the division method:

144 ÷ 2 = 72
72 ÷ 2 = 36
36 ÷ 2 = 18
18 ÷ 2 = 9
9 ÷ 3 = 3
3 ÷ 3 = 1

So, the prime factors are: 2 × 2 × 2 × 2 × 3 × 3
Which gives us:
144 = 2⁴ × 3²

 

5. What is 96 in prime factor form?

Answer:
To express 96 in prime factor form:

96 ÷ 2 = 48
48 ÷ 2 = 24
24 ÷ 2 = 12
12 ÷ 2 = 6
6 ÷ 2 = 3
3 ÷ 3 = 1

So, the prime factorization is: 2 × 2 × 2 × 2 × 2 × 3
In exponential form:
96 = 2⁵ × 3

 

Keep practicing prime factorization, explore solved examples, and master the methods with Orchids The International School. Make math easier and fun today!