Composite Numbers

Our world can’t function without understanding the functionality of numbers. Introducing numbers to your kids at tender age is essential, but did you find an easy way yet? Do you believe that number concepts can help your children academically? Numbers are the basis of mathematics; various kinds of numbers exist in mathematics, such as natural, prime, odd, cardinal numbers, etc., which kids must comprehend. Let’s discuss the vital topic of composite numbers excitingly. It would help you to make numeric concepts easier for your kids to remember.

What is a Composite Number?

Composite numbers are those numbers that are divisible by a number other than one and the number itself. In other words, numbers opposite to prime numbers with more than two factors are called composite numbers.

Types of Composite Numbers

In Mathematics, there are two types of composite numbers.

1. Odd Composite Numbers:

Odd composite numbers include all the odd integers that are not prime.

Examples of odd numbers are 9, 15, 21, 25, 27 etc.

2. Even Composite Numbers:

Even composite numbers include all the even integers that are not prime.

Examples of odd numbers are 4, 6, 8, 10, 12, 14, 16, etc.

How many composite numbers are between 1 and 100?

In mathematics, there are 74 composite numbers between 1 to 100. Here is the list of composite numbers.

Composite Numbers List from 1 to 100

4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100.

What Will Be the HCF of Two Composite Numbers?

We can understand that with the help of examples:

Example 1: What will be the HCF of two consecutive composite numbers, 4 and 6?

Solution: For the factorisation, we can write two numbers:

4=  2 x 2 

6= 3 x 2 

Now, we can see the highest common factor of 4 and 6 is 2.

Therefore, HCF(4,6)= 2, a prime number.

Example 2: What is the HCF of two composite numbers, 30 and 40?

Solution: For the factorisation, we can write two numbers:

30= 2 x  3 x  5

40= 2 x  2 x  2 x 5

Now, we can see the highest common factor of 30 and 40 is 2 and 5

HCF (30,40) = 2 x  5 = 10 

Therefore, HCF (30,40)= 10, a composite number.

The HCF of two composite numbers can be a prime number or composite number.

How Many Factors Does a Composite Number Have?

Every composite number has more than two factors. For example:

Factors of 15 = 1, 3, 5 and 15

Factors of 21 = 1,3, 7 and 21

Factors of 36 = 1, 2, 3, 4, 6, 9, 12, 18, and 36

Factors of 44 = 1, 2, 4, 11, 22 and 44

Factors of 87 = 1, 3, 29 and 87

Factors of 63 = 1, 3, 7, 9, 21 and 63

Factors of 51 = 1, 3, 17 and 51

Factors of 98 = 1, 2, 7, 14, 49 and 98

Factors of 49 = 1, 7 and 49

Factors of 55 = 1, 5, 11 and 55

What Are Prime Numbers and Composite Numbers?

Prime Numbers and Composite Numbers

Any positive number or positive integer that does not have more than two factors other than 1 or the number itself defines Prime Numbers. Numbers with no decimal or fractional part, including positive, negative and zero, are called Integers. Suppose n is the prime number; its factors must be n and 1. If any number’s factor is more than 2, it is called a “Composite Number”. 

There are 25 prime numbers between 1 to 100. The list of prime numbers is as follows:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

Example: 11 is divisible only by 11, and 1 is a prime number.

How to Find Composite Numbers?

Here are the simple steps to find the composite numbers:

1) Identify the positive integer factors.

2) If the number has factors such as 1 and the number itself, it is said to be a prime number.

3) If the number has more than two factors, it is a composite number. 

• Example 1:

Find if 22 is a composite number or a prime number.

22 ÷ 1 = 22

22 ÷ 2 = 11

22 ÷ 11 = 2

22 ÷ 22 = 1

As we can see, 22 has more than two factors, i.e., 22, 11, 2, and 1, so it is a composite number.

• Example 2: 

Find if 19 is a composite number or a prime number.

19 ÷ 1 = 19

19 ÷ 19 = 1

As we can see, 19 has only two factors, i.e., 19 and 1, so it is a prime number.

Frequently Asked Questions (FAQs)

1. Is 1 a Composite Number?

Answer: 1 is not a composite number. Every composite number has more than two factors, but 1 has only one factor, and that too is 1.

2. Which Is the Smallest Odd Composite Number?

Answer: The smallest odd-compound number is 9. It is because 1, 2, 3, 5, and 7 are prime numbers, and 4, 6, and 8 are even composite numbers.

3. Is 2 a Composite Number?

Answer: The positive integer 2 is not a composite number because it can be divided by only two factors, one and itself. Hence, 2 is a prime number.

4. Is 1 a Composite Number?

Answer: 1 is neither a prime number nor a composite number. 1 has only one factor, which is 1.

5. Are All Even Numbers Composite?

Answer: No, not all even numbers are composite numbers. All the prime numbers are odd, barring 2. But all even numbers, excluding 2, are composite numbers. Two is the prime number as it has only two factors, which are 2 and 1.

6. Which Number Is Neither Prime nor Composite?

Answer: 1 is the only number which is neither a prime nor a composite number. Because 1 has only one factor, which is 1 itself.

7. What Is the Smallest Composite Number?

Answer: 4 is the smallest composite number. Moreover, 1 is neither a prime nor a composite number, and 2 and 3 are prime numbers.