Wednesday, 16 May 2018



//Write a program to check number is perfect or not?
A perfect number is a positive integer that is equal to the sum of its proper positive divisors, 
that is, the sum of its positive divisors excluding the number itself. Equivalently, a perfect number
 is a number that is half the sum of all of its positive divisors. The first perfect number is 6, 
because 1, 2 and 3 are its proper positive divisors, and 1 + 2 + 3 = 6. Equivalently, 
the number 6 is equal to half the sum of all its positive divisors:
                               ( 1 + 2 + 3 + 6 ) / 2 = 6.


import java.util.Scanner;

public class PerfectNumber {
            public static void main(String[] args) {
                        int n,sum=0;
                        Scanner s1=new Scanner(System.in);
                        System.out.println("enter number");
                        n=s1.nextInt();
                        for(int i=1;i<n;i++)
                        {
                                    if(n%i==0)
                                    {
                                                sum=sum+i;
                                    }
                        }
                       
                        if(sum==n)
                        {
                                    System.out.println("Number is perfect");
                        }
                        else
                        {
                                    System.out.println("Number is not perfect");
                        }
                       
            }

}


o/p:---------------
enter number
6
Number is perfect

enter number
28
Number is perfect
enter number
45
Number is not perfect
======================================================================= 

package govind;

public class PerfectNo {
           
            public String checkPerfect(int n)
            {
                        int sum=0;
                        for(int i=1;i<=n/2;i++)
                        {
                                    if(n%i==0)
                                    {
                                                sum=sum+i;    
                                    }
                                   
                        }
           
                       
                        if(sum==n)
                        {
                                    return "Number is perfect";
                        }
                        else
                        {
                                    return "Number is not perfect";
                        }
            }
           
           
           
            public static void main(String[] args) {
                        PerfectNo pn=new PerfectNo();
                        String s1=pn.checkPerfect(28);
                        System.out.println(s1);
            }
           

}


o/p:---------
Number is perfect


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