calculate factorial error.

Question

what is wrong with my factorial code , it gives 0 output?

public static void Main()
{
    Console.WriteLine(Factorial(100));
    Console.ReadLine();
}

public static int Factorial(int num)
{
    int fact = 1;
    for (int i = num; i > 1; i--)
    {
        fact = fact * i;
    }
    return fact;
}