package com.rushilsrivastava.prime; import java.util.Scanner; public class PrimeByNumber { public static void main(String[] args) { System.out.println("How many prime numbers would you like to calculate? "); Scanner sc = new Scanner(System.in); int numbers = sc.nextInt(); //loop through the numbers one by one int counter = 0; int i = 0; while (counter < numbers) { boolean isPrime = isPrime((long) i); // print the number if (isPrime) { System.out.print(i + " "); counter++; } i++; } } public static boolean isPrime(long n) { if (n < 2) return false; if (n == 2 || n == 3) return true; if (n % 2 == 0 || n % 3 == 0) return false; long sqrtN = (long) Math.sqrt(n) + 1; for (long i = 6L; i <= sqrtN; i += 6) { if (n % (i - 1) == 0 || n % (i + 1) == 0) return false; } return true; } }