Question

A positive integer is said to be a perfect number if it equals the sum of its positive divisors (excluding the number itself). As an example, 6 is aperfect number because its divisors, 1, 2, and 3 sum up to 6. The first four perfect numbers are 6, 28, 496, 8128. Write a C program that asks the user to enter a number and checks if the number is perfect. Your program should run interactively until the user quits. Try to minimize the program execution time by using the least number of iterations for finding the divisors of the user's input. Record and report the number of iterations executed for checking if a number is perfect. Sample Code Execution: Red text indicates information entered by the user Enter a perfect number:1 Number 1 is not perfect Number of iterations:0 Do you want to continue (y/n)?y Enter a perfect number:6 Number 6 is perfect Number of iterations:3 Do you want to continue (y/n)?y Enter a perfect number:67 Number 67 is not perfect Number of iterations:33 Do you want to continue (y/n)?y Enter a perfect number:496 Number 496 is perfect Number of iterations:248 Do you want to continue (y/n)?n Goodbye

Answer 1

#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;
}

Answer 2

#include <iostream> #include <cctype>
using namespace std;
 int main(){
    int n,i=1,sum=0;
    cout << "Enter a number: ";
    cin >> n;
       while(i<n){
       if(n%i==0)
       sum=sum+i;
       i++; }
 if(sum==n)
    cout << i << " is a perfect number\n"; else
    cout << i << " is not a perfect number\n";
    system("pause"); return 0;}