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# C# Program to Check Whether the Entered Number is a Perfect Number or Not

###### Tutorialsrack 11/08/2019 C# Programs

In this C# program, we will learn how to write a program to check whether the entered number is a perfect number or not.

## What is a Perfect Number?

A perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself.

For Example, 6 has divisors 1, 2 and 3 (excluding itself), and 1 + 2 + 3 = 6, so 6 is a perfect number.

The sum of divisors of a number, excluding the number itself, is called its aliquot sum, so a perfect number is one that is equal to its aliquot sum. In other words, a perfect number is a number that is half the sum of all of its positive divisors including itself

I.e. σ1(n) = 2n

For Example, 28 is perfect as 1 + 2 + 4 + 7 + 14 + 28 = 56 = 2 × 28

Here is the code of the program to check whether the entered number is a perfect number or not:

##### Code - C# Program To Check Whether the Entered Number is a Perfect Number or Not
``````using System;

namespace TutorialsrackPrograms
{
class Program
{
//C# Program to Check Whether the Entered Number is a Perfect Number or Not.
static void Main(string[] args)
{
int number, sum = 0, n;
Console.Write("Enter The Number: ");
n = number;
for (int i = 1; i < number; i++)
{
if (number % i == 0)
{
sum = sum + i;
}
}
if (sum == n)
{
Console.WriteLine("\nEntered Number is a Perfect Number");
}
else
{
Console.WriteLine("\nEntered Number is not a Perfect Number");
}
}
}
}``````
##### Output

Enter The Number: 28

Entered Number is a Perfect Number