急需一个用c#编写的计算器程序

//此乃windows应用程序
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace MathCalc
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button3;
private System.Windows.Forms.Button Button_x;
private System.Windows.Forms.Button Button18a;
private System.Windows.Forms.Button button5;
private System.Windows.Forms.Button button6;
private System.Windows.Forms.Button Buttonadd;
private System.Windows.Forms.Button button4;
private System.Windows.Forms.Button Buttons;
private System.Windows.Forms.Button Buttonm;
private System.Windows.Forms.Button buttond;
pri