Prime Number

Prime Numbers are those natural numbers which are grater than 1 and which cannot be represented in the form of multiplication of two digits. They are divided by 1 and themselves only. Prime Number is one of the most puzzling number in the mathematics field. Many scientists around the globe spent their decades of time in finding the nature of the prime numbers.
For Example: 2, 3, 5, 7, 11, 13, 17 etc are prime numbers since they are only divisible by 1 and themselves.

How to find if a number is a prime Number?

Let us suppose a number N is given and we need to find if it is a prime or not. since, proving a number is prime, is much harder than proving a number is not a prime.
These are the steps to follow inorder to check if a number is prime or not:
Step 1 : Check if the number N is less than 2, then it is not a prime number.
Step 2 : Check if the number N is even and it is not 2 then also it is not a prime number.
Step 3 : Now you need to check if the number N is divisible by any odd number less than N and greater than 2. If N is divisible by any number then it is not a prime number. Otherwise, it is a prime number.

Example:
Check if 23 is a prime number or not?
Step 1 : 23 is greater than 2.
Step 2 : 23 is not a even number.
Step 3 : From 2 to 23, 23 is not divisible by any number.
So, 23 is a prime number.

Check if 24 is a prime number or not?
Step 1 : 24 is not less than 2.
Step 2 : 24 is an even number.
So, 24 is not a prime number.

Check if 15 is a prime number or not?
Step 1 : 15 is not less than 2.
Step 2 : 15 is not an even number.
Step 3 : between 2 to 15, 15 is divisible by 3,5.
So, 15 is not a prime number.

Applications of Prime Numbers

Prime Numbers are the most studied numbers in the mathematics. Since they cannot be divided by any other number except themselves and 1, they have a lot of applications in the real world. Some of the applications are:

Cryptography : Prime number is the heart of the modern encryption algorithms. RSA algorithm is considered one of the most secure encryption algorithms which is also based on the prime numbers. Our whole encryption system relied upon the difficulty level of factoring the product of two large prime numbers.Bigger the number greater the security.

Computer Science : Algorithms which can generate the prime numbers at high speed and more efficiently consuming less amount of memory are always in demand. From generating random number to making a hashing function, prime numbers are always needed.