Here is a java program to check whether a number is perfect number or not. A perfect number is a number whose sum of all the divisors is equal to the number itself.
Examples of Perfect Numbers :
6 = 1 + 2 + 3, (1, 2 and 3 are proper divisors of 6).
28 = 1 + 2 + 4 + 7 + 14 (1, 2, 4, 7, 14 are proper divisors of 28).
In this java program, we have to check whether a given number is an perfect number or not and print the result on screen.
Algorithm to check a number is perfect number or not
Let N be the given number.
Let N be the given number.
- Find all divisors of a N between 1 to N/2.
- Add the values of all divisors to a variable sum.
- If sum is equal to N, then N is a perfect number otherwise not a perfect number.
Java program to check perfect number or not
This program first takes a number as input from user and stores it in variable 'N'. Using a for loop, we iterate from 1 to N/2 to find the sum of all divisors of N. If divisor sum is equal to N, then N is a perfect number else not a perfect number.
package com.tcc.java.programs;
import java.util.Scanner;
public class PerfectNumber {
public static void main(String[] args) {
int N, i, divSum;
Scanner scanner;
scanner = new Scanner(System.in);
System.out.println("Enter an Integer");
N = scanner.nextInt();
/*
* Find the sum of all divisors of a N between 1 to N/2
*/
for (divSum = 0, i = 1; i <= N / 2; i++) {
if (N % i == 0) {
divSum += i;
}
}
if (divSum == N)
System.out.format("%d is Perfect Number", N);
else
System.out.format("%d is Not a Perfect Number", N);
}
}
Output
Enter an Integer 6 6 is Perfect Number
Enter an Integer 12 12 is Not a Perfect Number
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