static void Main(string[] args)
        {
            BinaryFormatter binaryFormatter = new BinaryFormatter();

            using (FileStream fileStream = new FileStream("a.ser", FileMode.Create))
            {
                Multiple multiple = new Multiple(new Random().Next(1, 10));
                binaryFormatter.Serialize(fileStream, multiple);
            }

            using (FileStream fileStream = new FileStream("a.ser", FileMode.Open))
            {
                Multiple multiple = binaryFormatter.Deserialize(fileStream) as Multiple;
                Console.WriteLine(multiple);
            }
        }
        static void Main(string[] args)
        {
            XmlSerializer xmlSerializer = new XmlSerializer(typeof(Multiple));

            using (FileStream fileStream = new FileStream("a.ser", FileMode.Create))
            {
                Multiple multiple = new Multiple(new Random().Next(1, 10));
                xmlSerializer.Serialize(fileStream, multiple);
            }

            using (FileStream fileStream = new FileStream("a.ser", FileMode.Open))
            {
                Multiple multiple = xmlSerializer.Deserialize(fileStream) as Multiple;
                Console.WriteLine(multiple);
            }
        }