Perfect Number Program in Java Example.

A Perfect Number is sum of its positive divisors, excluding the number itself. The First Perfect number is 6, For example 6 is a perfect number as 1,2 and3 are its divisors and the sum of divisors= ( 1 + 2 + 3)  = 6.

Algorithm for Perfect Number Program:

step 1: Read num

step 2: Set b=1, s=0

step 3: Repeat through step-5 until (b < num)

step 4: If (num mod b) equals to 0 then s=s+b

step 5: b=b+1

step 6: If s equals to num then print “num is perfect”

Else print “num is not perfect”

Step 7: Exit

Here is the Java Example for Perfect Number Program:

import java.util.Scanner; 
 class PerfectNumber 
 { 
     public static void main(String args[]) 
     { 
         Scanner sl=new Scanner(System.in); 
         System.out.println("Enter A Number"); 
         int num=sl.nextInt(); 
         
         int b=1, s=0; 
         
         while(b<num ) 
         { 
             if(num%b == 0) 
             { 
                 s += b; 
                
             } 
             b++; 
         } 
         
         if(s == num) 
         { 
             System.out.println(num+" is a perfect number"); 
         } 
        else 
         { 
            System.out.println(num+" is not a perfect number"); 
         }        
     } 
 }