100 Factorial + 1 in C# (BCL only)

Program.cs

using System;
using System.Linq;
using System.Numerics;

namespace Fact
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(Enumerable.Range(1, 100).Aggregate(new BigInteger(1), (b, i) => b *= i) + 1);
        }
    }
}