# Factorial in csharp

In this article we will learn about Factorial in csharp. Factorial of a number is obtained from the result of multiplying a series of descending natural numbers. Please read the previous article of Prime Number in csharp.

### What is Factorial number?

Factorial of a number is obtained from the result of multiplying a series of descending natural numbers. Factorial of n is the product of all positive descending integers. Factorial of n is denoted by n!.

Example:

```5! = 5*4*3*2*1 = 120
6! = 6*5*4*3*2*1 = 720```

Here, 5! is pronounced as “5 factorial”, it is also called “5 bang” or “5 shriek”.The factorial is normally used in Combinations and Permutations (mathematics).

### 3 Different ways to calculate Factorial in csharp

#### Using For Loop

```using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace factorial
{
class Program
{
static void Main(string[] args)
{
int i, number, fact;
Console.WriteLine("Enter the Number");
fact = number;
for (i = number - 1; i >= 1; i--)
{
fact = fact * i;
}
Console.WriteLine("\nFactorial of Given Number is: "+fact);
}
}
}```

Output:

```Enter the Number: 5
Factorial of Given Number is: 120```

#### Using Recursion

```class Program
{
static void Main(string[] args)
{
int number;
Console.WriteLine("Enter the Number");
double fact;
fact = factorial_Recursion(number);
Console.WriteLine("\nFactorial of Given Number is: " + fact);
}
public static double factorial_Recursion(int number)
{
if (number == 1)
return 1;
else
return number * factorial_Recursion(number - 1);
}
}```

Output:

```Enter the Number: 8
Factorial of Given Number is: 40320```

#### Using While Loop

```class Program
{
static void Main(string[] args)
{
int number;
Console.WriteLine("Enter the Number");
double fact;
fact = factorial_Recursion(number);
Console.WriteLine("\nFactorial of Given Number is: " + fact);
}
public static double factorial_Recursion(int number)
{
if (number == 1)
return 1;
else
return number * factorial_Recursion(number - 1);
}
}```

Output:

```Enter the Number: 4
Factorial of Given Number is: 24```

Hope It will clear about the Factorial in C#. Still have any question regarding this please give feedback.