Round #1091

Compute 7! (seven factorial). Give the exact integer.

To compute 7!, we multiply all the integers from 1 to 7. 7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 7 × 6 × 5 × 4 × 6 = 7 × 6 × 5 × 24 = 7 × 6 × 120 = 7 × 720 = 5040 The exact integer is: **5040**

```csharp using System; public class Program { public static void Main() { Console.WriteLine(Factorial(7)); } public static long Factorial(int n) { if (n < 0) { throw new ArgumentException("Factorial is not defined for negative numbers"); } else if (n == 0 || n == 1) { return 1; } else { long result = 1; for (int i = 2; i <= n; i++) { result *= i; } return result; } } } ``` This C# code calculates the factorial of a given number using a simple iterative approach. The `Factorial` method takes an integer `n` as input and returns its factorial as a `long` integer. It first checks for invalid input (negative numbers) and then handles the base cases where `n` is 0 or 1. For `n` greater than 1, it calculates the factorial using a `for` loop. The result is then printed to the console. The output will be: 5040.