怎么做一个简单的“计算器”

 //做一个简单的计算器
           {
               double a, b,c;
            Console.WriteLine("乘法");
            Console.Write("请输入第一个数：");
            a = Convert.ToDouble(Console.ReadLine());   //toDoule  变成Double类型

            Console.Write("请输入第二个数");
            b = Convert.ToDouble(Console.ReadLine());
            c = a * b;
            Console.WriteLine(a+"*"+b+"的结果为:"+c.ToString());
            Console.WriteLine("除法");
            Console.Write("请输入第一个数");
            a = Convert.ToDouble(Console.ReadLine());
            Console.Write("请输入第二个数");
            b = Convert.ToDouble(Console.ReadLine());
            c = a / b;
            Console.WriteLine(a + "/" + b + "的结果为:" + c.ToString());
         
               
               
               
               //等待命令关闭
            Console.ReadLine();}