public class CodSingleTon
    {
        private static CodSingleTon codInstance;
        private decimal _Result=0;
        private CodSingleTon()
        {
        }
       

        public static CodSingleTon Instance
        {
            get
            {
                if (codInstance == null)
                {
                    codInstance = new CodSingleTon();
                }
                return codInstance;
                
            }
        }
        public void AddNumbers(decimal _Value)
        {
            _Result = _Value;
        }

        public decimal GetResult()
        {
            return _Result;
        }
}
  private void button1_Click(object sender, EventArgs e)
        {
      

            CodSingleTon cls = CodSingleTon.Instance;
            CodSingleTon cls1 = CodSingleTon.Instance;
            cls.AddNumbers(Convert.ToDecimal(txtInput.Text));

            MessageBox.Show(cls.GetResult().ToString());
          
            cls1.AddNumbers(Convert.ToDecimal(txtInput.Text));
            MessageBox.Show(cls1.GetResult().ToString());

        
        }