using System;

using System.Diagnostics;

using System.Threading.Tasks;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var testClass = new TestClass();

        testClass.Calculate(1).GetAwaiter().GetResult();

​

        testClass.Calculate(2).GetAwaiter().GetResult();

​

        testClass.Calculate(4).GetAwaiter().GetResult();

    }

}

​

public class TestClass

    {

        private readonly ulong max = 40000000ul;

​

        // Sample class

        private class Sample

        {

            public double A { get; set; } = 1.0;

        }

​

        public async Task Calculate(int taskAmount)

        {

            var sw = Stopwatch.StartNew();

            await Task.WhenAll(Enumerable.Range(0, taskAmount).Select(_ => Task.Run(() => CalculateStuff(new Sample(), (max / (ulong)taskAmount)))));

            Console.WriteLine($"{taskAmount}: {sw.ElapsedMilliseconds}");

        }

​

        // Calculate some math stuff

        private static void CalculateStuff(Sample s, ulong max)

        {

            for (ulong i = 1; i <= max; i++)

            {

                s.A = Math.Pow(s.A, 1.2);

            }

        }

    }