程序代码：

using namespace System;
using namespace System::Numerics;

BigInteger Factorial(Int32 number);

void main(void)
{
    Int32 number(200);
    Console::WriteLine("{0}! = {1}", number, Factorial(number));
    Console::ReadLine();
}

// 计算指定数的阶乘
BigInteger Factorial(Int32 number)
{
    BigInteger result(1);

    if (number >= 0)
    {
        for (Int32 i = 1; i <= number; ++i)
        {
            result *= i;
        }
    }

    return result;
}