**What is a perfect number?**

“Perfect number is a positive number which sum of all positive divisors excluding that number.”

For example 6 is Perfect Number since divisor of 6 are 1, 2 and 3. Sum of its divisor is

1 + 2+ 3 =6

and 28 is also a Perfect Number

since 1+ 2 + 4 + 7 + 14= 28

Other perfect numbers: 496, 8128

### C++ Program

#include<iostream.h> #include<conio.h> void main() { clrscr(); int i=1, u=1, sum=0; while(i<=500) { while(u<=500) { if(u<i) { if(i%u==0 ) sum=sum+u; } u++; } if(sum==i) { cout<<i<<" is a perfect number."<<"\n"; } i++; u=1; sum=0; } getch(); }

### Output

6 is a perfect number. 28 is a perfect number. 496 is a perfect number.