## 1.04.2012

### 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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