Calculator using .NET c#

Copy this code and paste to c# .net

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
double total1 = 0;
double total2 = 0;

private void btnOne_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnOne.Text;
}

private void btnTwo_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnTwo.Text;
}

private void bynThree_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnThree.Text;

}

private void btnFour_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnFour.Text;
}

private void btnFive_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnFive.Text;
}

private void btnSix_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnSix.Text;
}

private void btnSeven_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnSeven.Text;
}

private void btnEight_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnEight.Text;
}

private void btnNine_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnNine.Text;
}

private void bynZero_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnZero.Text;
}

private void btnClear_Click(object sender, EventArgs e)
{
txtDisplay.Clear();
}

private void btnPlus_Click(object sender, EventArgs e)
{

total1 += double.Parse(txtDisplay.Text);
txtDisplay.Clear();

plusButtonClicked = true;
minusButtonClicked = false;
}

private void btnEqual_Click(object sender, EventArgs e)
{
if (plusButtonClicked == true)
{
total2 = total1 + double.Parse(txtDisplay.Text);
}
else if (minusButtonClicked == true)
{
total2 = total1 - double.Parse(txtDisplay.Text);

}
else if (multiButtonClicked == true)
{
total2 = total1 * double.Parse(txtDisplay.Text);

}
else if (divideButtonClicked == true)
{
total2 = total1 / double.Parse(txtDisplay.Text);
}
txtDisplay.Text = total2.ToString();
total1 = 0;
}

private void btnDot_Click(object sender, EventArgs e)
{
txtDisplay.Text = txtDisplay.Text + btnDot.Text;
}

private void Form1_Load(object sender, EventArgs e)
{

}

bool plusButtonClicked = false;
bool minusButtonClicked = false;
bool multiButtonClicked = false;
bool divideButtonClicked = false;

private void btnMultiply_Click(object sender, EventArgs e)
{
total1 += double.Parse(txtDisplay.Text);
txtDisplay.Clear();
multiButtonClicked = true;

}

private void btnMinus_Click(object sender, EventArgs e)
{
total1 += double.Parse(txtDisplay.Text);
txtDisplay.Clear();
plusButtonClicked = false;
minusButtonClicked = true;
}

private void btnDivide_Click(object sender, EventArgs e)
{
total1 += double.Parse(txtDisplay.Text);
txtDisplay.Clear();

divideButtonClicked = true;
}

private void button1_Click(object sender, EventArgs e)
{
this.Close();
}

private void saveToolStripMenuItem_Click(object sender, EventArgs e)
{

}

private void txtDisplay_TextChanged(object sender, EventArgs e)
{

}

}
}