Objetive

The factorial of a number is expressed as follows:

n! = n · (n-1) · (n-2) · (n-3) · ... · 3 · 2 · 1

For example,

6! = 6·5·4·3·2·1

Create a recursive function to calculate the factorial of the number specified as parameter:

Console.Write ( Factorial (6) );

would display 720

Solution

The factorial of a number is expressed as follows:

n! = n · (n-1) · (n-2) · (n-3) · ... · 3 · 2 · 1

For example,

6! = 6·5·4·3·2·1

Create a recursive function to calculate the factorial of the number specified as parameter:

Console.Write ( Factorial (6) );

would display 720

Solution

using System; public class Exercise120 { public static int Factorial(int num) { if (num == 0) return 1; else return num * Factorial(num-1); } public static void Main() { Console.WriteLine("Enter a number:"); int number = Convert.ToInt32(Console.ReadLine()); Console.WriteLine(Factorial(number)); Console.WriteLine ( Factorial (6) ); } }