Calculadora

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

namespaceWindowsApplication1
{
public partial class Form1 : Form
{
private double cal1=0;
private double cal2 = 0;
private double cal3 = 0;
private double cal4 = 0;
private double total = 0;
private int suma = 0;private int resta = 0;
private int multiplicacion = 0;
private int division = 0;
private int dec = 0;
private int men = 0;

public Form1()
{
InitializeComponent();
txtpatalla2.Visible = false;txtpatalla2.Enabled = false;
txtpatalla.Enabled = false;
lblcalc.Visible = false;
}

private void button3_Click(object sender, EventArgs e)
{

}

private void Form1_Load(object sender,EventArgs e)
{

}

private void button3_Click_1(object sender, EventArgs e)
{

if (dec == 1)
{
total = Convert.ToDouble(txtpatalla.Text += ",0");
txtpatalla.Visible = true;txtpatalla2.Visible = false;
}
else if (men == 1)
{
total = Convert.ToDouble(txtpatalla.Text += "-0");
txtpatalla.Visible = true;
txtpatalla2.Visible = false;
}
else
{
total = Convert.ToDouble(txtpatalla.Text+= "0");
txtpatalla.Visible = true;
txtpatalla2.Visible = false;
}

dec = 0;
men = 0;
}

private void btnuno_Click(object sender, EventArgs e)
{

if (dec == 1)
{
total=Convert.ToDouble(txtpatalla.Text += ",1");
txtpatalla.Visible = true;
txtpatalla2.Visible = false;
}
else if (men == 1)
{
total = Convert.ToDouble(txtpatalla.Text += "-1");
txtpatalla.Visible = true;txtpatalla2.Visible = false;
}
else
{
total = Convert.ToDouble(txtpatalla.Text += "1");
txtpatalla.Visible = true;
txtpatalla2.Visible = false;
}
dec = 0;
men = 0;

}

private voidbtndos_Click(object sender, EventArgs e)
{

if (dec == 1)
{
total =Convert.ToDouble(txtpatalla.Text += ",2");
txtpatalla.Visible = true;
txtpatalla2.Visible = false;
}
else if (men == 1)
{
total =...