Are you confused about the difference between the composite number and prime number? Don’t worry this article will help you to know about the difference between a composite number and a prime number. A natural number is classified into two types prime number and composite number. Here we will learn in-depth about composite numbers. Scroll down this page to gather the information on composite numbers such as definition, types, how to determine the composite numbers, list of composite numbers, the difference between composite and prime number, etc.
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Composite Number – Definition
A composite number is a positive integer that can be formed by multiplying two small positive integers. In maths, composite numbers are the type of natural numbers that have more than three factors. The natural numbers that are not prime numbers are called composite numbers.
Example: 4, 6, 8, 9 are the composite numbers.
Types of Composite Numbers
There are two types of composite numbers. They are as follows,
1. Even composite number
2. Odd composite number
1. Even composite number: All even numbers that are not prime are called even composite numbers.
4, 6, 8, 10, 12, 14 are examples of composite even numbers.
2. Odd composite number: All odd numbers that are not prime are called even composite numbers.
9, 15, 21 are examples of composite odd numbers.
Smallest Composite Numbers
1 is not a composite number because it has only one divisor 1. 2 and 3 have only two factors one and itself. In the case of 4, there are more than two factors. The factors of 4 are 1, 2, 4. So, the smallest composite number is 4.
The smallest prime number is 2.
The smallest odd composite number is 9.
The two-digit smallest composite number is 12.
Three digits smallest composite number is 100.
How to Determine if a Number is Composite or Not?
The procedure to find whether the given number is a composite number is given below,
1. Find all the factors of the positive integer.
2. A number is said to be a prime, if and is the given number has only two factors i.e, 1 and itself.
3. If the number has more than two factors then it is a composite number.
Example: Find if 21 is a composite number.
Solution:
Let us find the factors of 21.
21 ÷ 1 = 21
21 ÷ 3 = 7
21 ÷ 7 = 3
21 ÷ 21 = 1
Thus the factors of 21 are 1, 3, 7 and 21.
So, the number 21 is a composite number.
Composite Numbers List from 1 to 100
Here we enlisted the composite numbers from 1 to 100. We suggest the students go through the list of composite numbers from 1 to 100 and try to write the composite numbers beyond them for practice.
Difference between Composite Numbers and Prime Numbers
Go through the below table to know the difference between the composite number and prime number.
|
Composite Number |
Prime Number |
| 1. Composite Numbers are natural numbers that have more than two factors. | 1. Prime numbers are the positive integers that have only two factors i.e, one and itself. |
| 2. Composite numbers can be divided by any other number including 1 and itself. | 2.Prime numbers can be divided by one and itself. |
| 3. Example: 4, 6, 8, 9 are examples of composite numbers. | 3. 2, 3, 5, 7 are examples of prime numbers. |
Properties of Composite Numbers
Go through the properties of Composite numbers to understand the concept in detail.
1. The composite numbers are the set of natural numbers which has 3 or more factors.
2. The number 4 is the smallest composite number.
3. Every composite number can be written as the product of two or more prime numbers.
4. A composite number with three different factors is known as sphenic numbers.
5. The number ‘1’ will not be considered as a composite number.
6. All even numbers except ‘2’ are composite numbers.
Prime Factorization of Composite Numbers
The list of composite numbers from 1 to 20 is given here with their prime factorization. Go through the below table to see the prime factorization of the composite numbers.
| Composite Number | Prime Factorization |
| 4 | 2 × 2 |
| 6 | 2 × 3 |
| 8 | 2 × 2 × 2 |
| 9 | 3 × 3 |
| 10 | 2 × 5 |
| 12 | 2 × 2 × 3 |
| 14 | 2 × 7 |
| 15 | 3 × 5 |
| 16 | 2 × 2 × 2 × 2 |
| 18 | 2 × 3 × 3 |
| 20 | 2 × 2 × 5 |
Composite Numbers Examples
Let us see some examples of composite numbers for better understanding.
Example 1.
What are the composite numbers from 1 to 10?
Solution:
Composite numbers from 1 to 10 are 4, 6, 8, 9
Example 2.
Write any two even composite numbers?
Solution:
4 and 6 are the two even composite numbers.
Example 3.
Write the smallest odd composite number?
Solution:
9 is the smallest odd composite number. Because 9 has more than 1 factor.
Example 4.
Determine whether 24 is a composite number or not?
Solution:
Yes, it is a composite number because it is divided by more than one number like 2, 3, 4, 6, 8, 12, and 24 so it is a composite number.
Example 5.
Write any two odd composite numbers?
Solution:
9 and 15 are the two odd composite numbers
FAQs on Composite Numbers
1. What is a composite number?
A composite number is a positive integer that has more than 1 factor.
2. What is the smallest composite number?
4 is the smallest composite number.
3. Is 1 a composite number?
No, because 1 does not have more than two factors. Hence 1 is neither composite nor a prime number.