using System;

namespace UseAMemoryStream
{
    using System;
    using System.IO;
    using System.Text;

    class Program
    {
        static void Main(string[] args)
        {
            using (var ms = new MemoryStream())
            {
                using (var sw = new StreamWriter(ms))
                {
                    sw.WriteLine("Wartość wynosi {0:0.00}.", 123.45678);
                }
                Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));
            }
        }
    }
}