Pi

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

namespace ConsoleApplication10
{
    class Program
    {
        static void Main(string[] args)
        {
            double pi =1;
            double a = 2, b = 1;
            for (int i = 0; i < 100000; i++)
            {
                double local = a / b;

                if (i % 2 != 0)
                {
                    a = a + 2;
                }
                else
                {
                    b = b + 2;
                }

                pi = pi * local;

            }
            pi = pi * 2;
            Console.WriteLine(pi);
        }
    }
}