btnTest1.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;
using System.Diagnostics;
using System.Threading;

namespace testy_wp
{
    public partial class Test1 : PhoneApplicationPage
    {
        public Test1()
        {
            Stopwatch stopwatch = new Stopwatch();
            stopwatch.Start();
            double pi = 0;
            for (int i = 1; i < 1000000000; i += 4)
            {
                pi += 8.0 / (i * (i + 2L));
            }
            stopwatch.Stop();
            WynikTest1.Text = (pi + stopwatch.Elapsed.TotalMilliseconds.ToString()  + " zajęło  ");
        }
    }
}