PERFECT NUMBER
A positive number is said to be perfect number if it is equal to the sum of its divisors.
For example,
The divisors of 6 are 1,2 and 3 and 1+2+3 = 6. Thus 6 is a perfect number.
The divisors of 28 are 1,2,4,7 and 14 and 1+2+4+7+14 = 28. Thus 28 is a perfect number.
STEPS
1. Initialize a variable sum with 0.
2. Input the number(num) from the user.
3. Initialize a counter (i) with 1.
4. Check the divisibility of num with i.
5. If it is divisible then add i to sum.
6. Increment counter(i).
7. Repeat steps 4-6 until i<=(num/2).
8. If sum is equal to num, then it is a perfect number else not.
PROGRAM
// Program to check whether given number is perfect number or not.
#include <iostream>
using namespace std;
int main()
{
int num ,sum=0 ,i;
cout<<"ENTER A NUMBER: ";
cin>>num;
for(i=1;i<=(num/2);i++)
{
if(num % i==0)
{
sum = sum + i;
}
}
cout<<endl;
if(sum==num)
{
cout<<num<<" IS A PERFECT NUMBER";
}
else
{
cout<<num<<" IS NOT A PERFECT NUMBER";
}
return 0;
}
OUTPUT
