Q. Java Program to Check Whether the Given Number Is Perfect Number or Not.

Here you will find an algorithm and program in Java programming language to check whether the given number is perfect number or not. First let us understand what Perfect number means.

Explanation : Perfect number is a positive integer equal to the sum of its proper divisors.

For Example : 6 is perfect number because sum of its proper divisor(1, 2, 3) is equal to 6.

START
Step 1 - Input the number.
Step 2 - Find all divisors of the number except the number itself.
Step 3 - If the sum of all divisors of the number is equal to the number, then return true. Else, return false.
STOP

Java Program to Check Perfect Number

public class LFC {
  public static void main(String[] args) {
    int i, num=28, Sum = 0 ;
    for(i = 1 ; i < num ; i++) {
      if(num % i == 0)  {
        Sum = Sum + i;
      }
    }
    if (Sum == num) {
      System.out.format("% d is a Perfect Number", num);
    }
    else {
      System.out.format("% d is NOT a Perfect Number", num);
    }
  }
}

Output

28 is a perfect number.