using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;namespace Math{  public partial class Form1 : Form  {    public Form1()    {      InitializeComponent();    }    System.Random t=new System .Random() ;//初始化隨機數函數    string num;//定義一個字符串變量，用于顯示    private void button1_Click(object sender, EventArgs e)    {      timer1.Start();    }    private void button2_Click(object sender, EventArgs e)    {      timer1.Stop();    }    private void timer1_Tick(object sender, EventArgs e)    {      this.num = Convert.ToString(t.Next(1,1000));//產生1到1000之間的一個隨機數      textBox1.Text = num;    }    private void button3_Click(object sender, EventArgs e)    {      this.Close();//關閉程序    }  }}