# Factorial program in C# – Simple ways to find factorial of a number

Factorial program in C# with example and logic. l

For Example to find the factorial of a number 6 is 720.
(6!=6*5*4*3*2*1=720)

## How to find factorial?

The factorial of a number denoted as n!.

Factorial Formula.

n!=n*(n-1)*(n-2)*…*1

For suppose to find the factorial of a number 6 as based on above formula.
6!=6*(6-1)*(6-2)*(6-3)*(6-4)*(6-5)
=6*5*4*3*2*1
=720

Notes:

• The factorial number is product of number in its descending order.
• Factorial of 0 is 0!=1
• No factorial for Negative Number.

## Example of factorial program in C# using for loop

``````using System;
/*
C# example for finding factorial of a number using for loop
*/

class Program
{
static void Main(string[] args)
{
//initialized number by 6
int number = 6;

//initialized factorial by 1
int factorial=1;
for (int j = number; j >= 1; j--)
{
factorial = factorial * j;

}
Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
}
}
}

``````

### Output

the factorial of the number 6 = 720

## Example of factorial program in C# using while loop

``````/*
C# example for finding factorial of a number using while loop
*/

class Program
{
static void Main(string[] args)
{
//initialized number by 6
int number = 6;

//initialized factorial by 1
int factorial=1;

int j = number;

while (j >= 1)
{
factorial = factorial * j;
j = j - 1;
}
Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
}
}
``````

## Example of factorial program in C# using do-while loop

``````  class Program
{

static void Main(string[] args)
{
//initialized number by 6
int number = 6;

//initialized factorial by 1
int factorial=1;

int j = number;

do
{
factorial = factorial * j;
j = j - 1;

} while (j >= 1);

Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
}
}
``````

## Example of factorial program in C# using function

``````
class Program
{

static void Main(string[] args)
{
//initialized number by 6
int number = 6;

//initialized factorial by 1
int factorial=1;

Program p = new Program();
//call the function by passing value to find the factorial
factorial = p.fact(number);

Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
}

public int  fact(int number)
{
int factorial = 1;
int j = number;
while (j >= 1)
{
factorial = factorial * j;
j = j - 1;
}
return factorial;
}
}
``````

## Example of factorial program in C# using Recursive function

``````
class Program
{

static void Main(string[] args)
{
//initialized number by 6
int number = 6;

//initialized factorial by 1
int factorial=1;

Program p = new Program();
factorial = p.fact(number);

Console.WriteLine("the factorial of the number " + number + "  =" + factorial);
}

public int fact(int number)
{

if (number==0 || number==1)
{
return 1;
}
else
{
return number * fact(number - 1);
}

}

}
``````
Factorial program in C# – Simple ways to find factorial of a number

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