Calculating pi using infinite series in C#

Question

Hi! I tried to write the following program in C# to calculate pi using infinite recursion, but I keep getting confused about integer/double/decimal division.

I really have no clue why this isn't working, so pardon me for my lack of understanding of strongly typed stuff, as I'm still learning C#.

Thanks in advance!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        public static int Main(string[] args)
        {
            int numeratornext = 2;
            int denominatornext = 5;

            decimal findto = 100.0M;
            decimal pi = 0.0M;
            decimal halfpi = 1.0M;
            int seriesnum = 1;
            int seriesden = 3;

            for (int i = 0; i < findto; i++)
            {
                halfpi += Decimal.Divide((decimal)seriesnum, (decimal)seriesden);
                //System.Console.WriteLine(Decimal.Divide((decimal)seriesnum, (decimal)seriesden).ToString());
                seriesnum *= numeratornext;
                seriesden *= denominatornext;
                numeratornext++;
                denominatornext += 2;
            }

            pi = halfpi * 2;

            System.Console.WriteLine(pi.ToString());
            System.Console.ReadLine();
            return 0;
        }
    }
}