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

Here you will find an algorithm and program in C 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

Perfect Number Program

//C program to check whether the given number is Perfect Number or not
#include <stdio.h>
int main()
{
  int num=28,i;
  int sum;
  sum=0;
  for(i=1; i< num;i++)
  {
    if(num%i==0)
      sum+=i;
  }
  if(sum==num)
    printf("%d is a perfect number.",num);
  else
    printf("%d is not a perfect number.",num);
  return 0;
}

Output

28 is a perfect number.