Difference Between Prime and Composite Numbers

Prime vs Composite Numbers

Math can be fun for those who understand the concepts but it can be a nightmare for those who take it casually. This applies very well to prime and composite number concept which is quite simple and easy to understand. But those who cannot differentiate between these two types of numbers often fare miserably in their math exams. This article will highlight the differences between prime number and composite number so that they become clear in the minds of the readers.

Prime numbers

We know what are natural numbers, don’t we? All numbers from one onwards are called natural numbers and are written as

{1, 2, 3, 4, 5, 6…}

Now a Prime Number is a natural number that leaves no remainder when divided by either itself or one. Prime number is not divisible by any other except these two numbers. This implies that there are only two factors of a prime number as it is not divisible by any other number. Let us see through example.

7= 1 x  7

5= 1 x  5

11= 1 x 11

Composite Numbers

Any natural number which is divisible by any other number apart from one and itself is called a composite number. Let us take up examples.

9 is a number that is divisible by 3 apart from 9 and 1 which means that it is a composite number. The same can be said about 8, 10, 12, 15, 18 or other similar numbers as they are divisible by a number other than itself and 1.

Interestingly, except 2, all other prime numbers are odd numbers, for example, 3, 5, 7, 11, 13, 17, and so on. All integers greater than 2 and divisible by 2 are composite numbers. Similarly, though 5 is a prime number, all numbers ending in 5 and greater than 5 are composite numbers.

0 and 1 are neither prime nor composite numbers.