# Java Program To Check A Number Is Prime or Not

In this post, we are going to learn, a number entered by the user is a prime number or not by using Java program.

### What is a prime number?

The number which is not divisible by any number other than 1 and the number itself, is known as Prime Number.

**Example: **suppose a number is 13. 13 is divisible by only 1 and 13 so it’s a prime number.

11, it is divisible by 1 and 11 only so it is also a prime number.

But no 14, it is divisible by 1,2,7,14 so it is not a prime number.

The numbers less than 1 are all non-prime numbers.

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### Java Code to check a number is prime or not:

import java.util.Scanner; public class Codespeedy { static int p; public static void main(String []args) { Scanner input=new Scanner(System.in); System.out.println("Enter a Number:"); int n=input.nextInt(); if(n<1){ System.out.println(n+" is not a prime number"); } else { for(int i=2;i<n;i++){ if(n%i==0){ System.out.println(n+" is not prime number"); p=1; break; } } if(p!=1){ System.out.println(n+" is a prime number"); } } } }

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**Output:**

run: Enter a Number: 13 13 is a prime number BUILD SUCCESSFUL (total time: 2 seconds)

### Explanation and algorithm of this program:

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**Step 1:** take a static int p, p is defined “static” because we want to access it globally.

**Step 2:** take a variable integer type n, and take input from the user, store it into n.

**Step 3:** Apply condition, If the number is less than 1 then it’s obviously Not A Prime Number.

**Step 4:** If the condition is false then it will run a loop starting from 2 and ending with n-1. because we know that every number is divisible by 1 and the number itself. So we will check if any other number is available there in between 1 to n which can divide the number, i,e (n%i==0)

**Step 5:** If we find a number like that which can divide our number then we will print n is not a prime number.

And we will assign 1 to “p”.

**Step 6:** If no number is found between 1 to n which can divide our number then we will simply print it’s a prime number. In order to that, we just make a condition after our for loop. If p is not equal to 1 then it is a prime number.( because for prime number we have assigned p=1)

break;

is used to end our loop. otherwise, the loop will keep printing same line.

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