public string check_number(string num_str)
        {

            num_str = num_str.Trim();

            if (Regex.IsMatch(num_str, @"^\d+(\.\d+)?$|^\d+(\,\d+)+(\.\d+)?$"))
            {
                this.Nonum = true;
                return num_str.Replace(",", "");
            }
            else
            {
                this.Nonum = false;
                return num_str;

            }

        
        }

eg:1.00
123,123
456,123.00