## Algorithm

Prime numbers are those which are not divisible by any other number apart from 1 and the number itself. Zero (0), one (1) and negative numbers (e.g., -2, -3, -5) are not prime numbers.

## Java Code

package com.physicsinfo; import java.util.Scanner; public class Main { public static void main(String[] args) { int n, flag=0; System.out.print("Enter a whole number(integer): "); Scanner sc = new Scanner(System.in); n = sc.nextInt(); if (n==0 || n==1|| n<0) {// 0,1 and negative numbers are not prime numbers flag=1; } if (n!=0 && n!=1) { for (int i = 2; i <= n / 2; i++) { if (n % i == 0) { //prime numbers aren't divisible by any other number apart from 1 and the number itself flag = 1; } } } if(flag==0){ System.out.println(n +" is a prime number.");} else { System.out.println(n +" is not a prime number."); } } }