import java.util.*; public class Prime { public static void main(String[] args) { Scanner scn = new Scanner(System.in); int t = scn.nextInt(); for (int j = 0; j < t; j++) { int n = scn.nextInt(); if (n <= 0) { System.out.println("number must be greater than 0!"); continue; } if (checkPrimeOrNot(n)) System.out.println("Number is prime"); else System.out.println("Number is not prime"); } scn.close(); } /* * This is the optimised code for checking if number is prime or not. * TC-O(sqrt(n)); It is three times faster than O(sqrt(n)) */ static boolean checkPrimeOrNot(int num) { if (num == 1) return false; if (num == 2 || num == 3) return true; if (num % 2 == 0 || num % 3 == 0) return false; for (int i = 5; i * i <= num; i++) { if (num % i == 0 || num % (i + 2) == 0) return false; } return true; } }