如何从控制台读取连续的输入行以用于Add()方法?

我的代码如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace JeffOrrisSimpleCalculator._1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Simple Calculator");
            Console.WriteLine("'t1> Add");
            Console.WriteLine("'t2> Subtract");
            Console.WriteLine("'t3> Multiply");
            Console.WriteLine("'t4> Divide");
            Console.WriteLine("'t5> Quit");
            Console.WriteLine();
            Console.Write("Enter Selection:  ");
            string myValue = ValidateData();
            Console.WriteLine(myValue);
            Console.Write("Enter number one:  ");
            Console.ReadLine();
            Console.Write("Enter number two:  ");
            Console.ReadLine();
            string mySum = Add();
            Console.WriteLine(mySum);
            Console.Read();
        }//end main
        private static string ValidateData()
        {

            string temp = Console.ReadLine();
            if ((temp == "1") || (temp == "2") || (temp == "3") || (temp == "4") ||                (temp == "5"))
            {
                //string Response = "Thank You";
                //return Response;
                return null;
            }
            else
            {
                string Response = "Please enter a valid selection";
                return Response;
            }
        }//end ValidateData

        private static string Add()
        {
            string numberOne = Console.ReadLine();
            double temp1 = Convert.ToDouble(numberOne);
            string numberTwo = Console.ReadLine();
            double temp2 = Convert.ToDouble(numberTwo);
            double total = temp1 + number2;
            string myTotal = Convert.ToString(total);
            return myTotal;
        }

        }//end class
        }//end namespace

*我只关心add方法。我提示用户输入我需要使用add方法添加的2个数字。我想我想多了。我习惯使用windows窗体，而不是控制台应用程序。我不知道如何从Console.ReadLine.

Console.Write("Enter number one:  ");
Console.ReadLine();
Console.Write("Enter number two:  ");
Console.ReadLine();

Console.Write("Enter number one:  ");
string firstLine = Console.ReadLine();
Console.Write("Enter number two:  ");
string secondLine = Console.ReadLine();