This is java:

import java.util.Scanner; public class IsPrime { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print("Enter a number : "); int n = s.nextInt(); if (isPrime2(n)) { System.out.println(n + " is a prime number."); } else { System.out.println(n + " is not a prime number."); } } public static boolean isPrime2 (int n){ boolean noFactors=true; if (n<= 1) return false; for (int m=2;noFactors;m++) { if (m*m>n) break; if (n%m==0) noFactors = false; } return noFactors; } } Make isPrime even more efficient by testing only potential factors that are relatively prime with 6 (that is, factors that are not evenly divisible by either 2 or 3).