Question

Please write a JAVA program which reads a number n from the user and check whether n is a perfect number or not. For example, when n = 7, the print out should be 7 is not a perfect number. If the input n is 6, then the program prints out 6 = 1 * 2 * 3

Answer 1

import java.util.Scanner;

public class PerfectNumber {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a positive integer: ");
        int n = in.nextInt();
        int result = 1;
        for (int i = 1; i < n; i++) {
            if (n % i == 0) {
                result *= i;
            }
        }
        if (result != n) {
            System.out.println(n + " is not a perfect number");
        } else {
            System.out.print(n);
            for (int i = 1; i < n; i++) {
                if (n % i == 0) {
                    if (i == 1) {
                        System.out.print(" = 1");
                    } else {
                        System.out.print(" * " + i);
                    }
                }
            }
            System.out.println();
        }
    }
}