## What Are Composite Numbers?

In math, **composite numbers can be defined as numbers that have more than two factors**. Numbers that are not prime are composite numbers because they are divisible by more than two numbers.

**Examples:**

- Factors of 4 = 1, 2, 4 i.e.

Since 4 has more than two factors. So, 4 is a composite number.

- Factors of 6 = 1, 2, 3, 6

Since 6 also has more than two factors. So, 6 is also a composite number.

Following is the **list of composite numbers from 1 to 100:**

**Fun Facts**

- The numbers 0 and 1 are neither prime nor composite numbers.
- All even numbers except 2 are composite numbers.
- 4 is the smallest composite number.
- Each composite number can be written as a product of two or more primes.
- Composite numbers are divisible by other composite numbers.
- All composite numbers are always divisible by 1 and the number itself.

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Finding Composite Numbers

The divisibility test is a standard method used to find a composite number. In this test, the given number is divided by a smaller prime or composite number. If it is entirely divisible, the number is a composite number.

For example, 48 = $2 \times 2 \times 2 \times 2 \times 3$

Since 48 is divisible by 2 and 3, hence it is a composite number.

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## Types of Composite Numbers

There are two types of composite numbers:

- Odd composite numbers
- Even composite numbers

### Odd Composite Numbers

Composite numbers with an odd digit in the unit’s place are odd composite numbers. In simple words, **all the odd numbers that are not prime numbers are odd composite numbers**.

**For example: 9, 15, 21, etc.**

### Even Composite Numbers

Composite numbers with an even digit in the unit’s place are even composite numbers. In simple words, **all the even numbers except 2 are even composite numbers**. This is because **no even number (except 2) can ever be a prime number**.

**For example: 8, 12, 14, etc.**

## Conclusion

A composite number is a positive integer divisible by smaller positive integers other than 1 and itself. Composite numbers can be identified by using the divisibility method.

## Solved Examples on Composite Numbers

**1. Check if 104 is a composite number or not.**

The given number 104 is divisible by 2 and hence have more than 2 factors.

Therefore, it is a composite number.

**2. Check if 111 is a composite number.**

The given number is divisible by 3 and hence have more than 2 factors.

Therefore, it is a composite number.

**3. Check if 179 and 144 are composite numbers.**

Among the given numbers, 179 is not divisible by any number other than 1 and 179; therefore, it is not a composite number. 144 is divisible by 2, so it is a composite number.

## Practice Problems on Composite Numbers

## Composite number

### Which is the smallest composite number among the following?

9 is the smallest composite number. It has more than two factors: 1, 3, and 9.

### Which one of the following is not a composite number?

23 is not a composite number. It is only divisible 1 and itself.

### Which of the following is a composite number?

20 is a composite number. It is divisible by more than two factors: 1, 2, 4, 5, 10, and 20.

### What is the largest composite number among the following?

39 is the largest composite number among all the options with 1, 3, 13, and 39 as its factors. 47 is a prime number.

## Frequently Asked Questions on Composite Numbers

**Can a number be both prime and composite?**

No, a number cannot be both prime and composite. A prime number has exactly two factors, 1 and itself, while a composite number has more than two factors. So, all natural numbers (except 1) are either prime or composite, but not both.

**Is 0 a composite number?**

Any number multiplied by zero gives the product 0. Hence 0 has an infinite number of factors. To be composite, a number must have more than two factors but not an infinite number of them. Hence, 0 does not qualify as a composite number.

**What is the smallest composite number?**

4 is the smallest composite number.

**Are all even numbers composite numbers?**

No. All even numbers except 2 are composite numbers. 2 has only two factors: 1 and 2.