gistfile1.cs

using System;
using System.Linq;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            foreach (var x in Enumerable.Range(0, 10))
            {
                var sum = 0;
                Parallel.For(0, 50000, i =>
                                       {
                                           sum += i;
                                       });

                Console.WriteLine("Parallel.For: {0}", sum);
            }

            Console.WriteLine("AsParallel.Sum: {0}", Enumerable.Range(0, 50000).AsParallel().Sum());

            Console.Read();
        }
    }
}