Perfect number

Q. Write a C program to check whether a given number is a perfect number or not.

Ans.

Definition of Perfect number: A positive integer n is called a perfect number if it is equal to the sum of all of its positive divisors, excluding n itself.

For example, 6 is perfect integer number, because 1, 2 and 3 are its proper positive divisors and 1+2+3=6.

The next perfect number is 28 because 1+2+4+7+14=28.

The next perfect number is 496 because

1+2+4+8+16+31+62+124+248=496.

/*program to check whether a number is perfect or not*/

#include<stdio.h>

#include<conio.h>

int main()

{

 int i,n,num,sum=0;

 printf("Enter a number : ");

 scanf("%d",&num);

 n=num;

 for(i=1; i<n; i++)

 {

  if(num%i==0)

     sum=sum+i;

 }

 if(num==sum)

  printf("Given number is Perfect Number ");

 else

  printf("Given number is Not Perfect Number ");
 getch();
 return 0;

}

Output:-

Enter a number : 7543

Given number is Not Perfect Number

Enter a number : 8128

Given number is Perfect Number

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