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**Factorial Program in C# with Examples**

In this article, I am going to discuss the **Factorial Program in C#** with some examples. Please read our previous article where we discussed the **Armstrong Number Program in C#** with examples. In many interviews, the interviewer asked this question in many different ways. As part of this article, we are going to discuss the following pointers.

**What is factorial of a number?****Factorial of a number using for loop, while loop and do-while loop in C#.****Factorial of a number using the recursive function in C#.**

**What is Factorial of a number?**

The Factorial of a number (let say n) is nothing but the product of all positive descending integers of that number. Factorial of n is denoted by n!. Please have a look at the following image which shows how to calculate the factorials of a number.

**Factorial Program in C# using for loop:**

In the following example, we take the number from the console and then calculate the factorial of that number using for loop.

using System; namespace LogicalPrograms { class Program { static void Main(string[] args) { Console.Write("Enter a Number : "); int number = int.Parse(Console.ReadLine()); int factorial = 1; for (int i = 1; i <= number; i++) { factorial = factorial * i; } Console.Write($"Factorial of {number} is: {factorial}"); Console.ReadLine(); } } }

**Output:**

**Factorials of a number using while loop in C#:**

In the following example, we use while loop to calculate the factorial of a number.

using System; namespace LogicalPrograms { class Program { static void Main(string[] args) { Console.Write("Enter a Number : "); int number = int.Parse(Console.ReadLine()); long factorial = 1; while (number != 1) { factorial = factorial * number; number = number - 1; } Console.Write($"Factorial is: {factorial}"); Console.ReadLine(); } } }

**Output:**

**Factorial of a number using Recursive Function in C#:**

In the following program, we use a recursive function to calculate the factorial of a given number.

using System; namespace LogicalPrograms { class Program { static void Main(string[] args) { Console.Write("Enter a Number : "); int number = int.Parse(Console.ReadLine()); long factorial = RecursiveFactorial(number); Console.Write($"Factorial of {number} is: {factorial}"); Console.ReadLine(); } static long RecursiveFactorial(int number) { if (number == 1) { return 1; } else { return number * RecursiveFactorial(number - 1); } } } }

**Output:**

**Factorial of a number using the do-while loop in C#:**

In the below program, we use the do-while loop to calculate the factorial of a given number. The number here we are taking from the console.

using System; namespace LogicalPrograms { class Program { static void Main(string[] args) { Console.Write("Enter a Number : "); int number = int.Parse(Console.ReadLine()); long factorial = 1; do { factorial = factorial * number; number--; } while (number > 0); Console.Write($"The Factorial is: {factorial}"); Console.ReadLine(); } } }

**Output:**

In the next article, I am going to discuss the **Sum Of Digits Program in C#** with some examples. Here, in this article, I try to explain the different ways to implement the **Factorial Program in C#** with examples.