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 Калькулятор
{
     public partial class Form1 : Form
     {
         bool plus = false;
         bool minus = false;
         bool ymnogit = false;
         bool delenie = false;

         public Form1()
         {
             InitializeComponent();
         }

          private void button1_Click(object sender, EventArgs e)
         {
             textBox1.Text = textBox1.Text + "7";
         }

          private void button2_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "8";
          }

          private void button3_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "9";
          }

          private void button5_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "4";
          }

          private void button6_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "5";
          }

          private void button7_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "6";
          }

          private void button9_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "1";
          }

          private void button10_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "2";
          }

          private void button11_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "3";
          }

          private void button13_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "0";
          }

          private void button14_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + "00";
          }

          private void button15_Click(object sender, EventArgs e)
          {
              textBox1.Text = textBox1.Text + ",";
          }

          private void button21_Click(object sender, EventArgs e)
          {
              textBox1.Text = "";
              textBox1.Tag = "";
          }

          private void button19_Click(object sender, EventArgs e)
          {
              double x;
              x = Convert.ToDouble(textBox1.Text) * Convert.ToDouble(textBox1.Text);
              textBox1.Text = Convert.ToString(x);
          }

          private void button20_Click(object sender, EventArgs e)
          {
              double k;
              k = Convert.ToDouble(textBox1.Text);
              textBox1.Text = Convert.ToString(Math.Sqrt(k));
          }

          private void button16_Click(object sender, EventArgs e)
          {
              plus = true;
              textBox1.Tag = textBox1.Text;
              textBox1.Text = "";  
          }

          private void button12_Click(object sender, EventArgs e)
          {
              minus = true;
              textBox1.Tag = textBox1.Text;
              textBox1.Text = "";  
          }

          private void button18_Click(object sender, EventArgs e)
          {
              ymnogit = true;
              textBox1.Tag = textBox1.Text;
              textBox1.Text = "";  
          }

          private void button8_Click(object sender, EventArgs e)
          {
              delenie = true;
              textBox1.Tag = textBox1.Text;
              textBox1.Text = "";  
          }

          private void button17_Click(object sender, EventArgs e)
          {
              if (plus)
              {
                  decimal del = Convert.ToDecimal(textBox1.Tag) + Convert.ToDecimal(textBox1.Text);
                  textBox1.Text = del.ToString();
              }
              if (minus)
              {
                  decimal del = Convert.ToDecimal(textBox1.Tag) - Convert.ToDecimal(textBox1.Text);
                  textBox1.Text = del.ToString();
              }
              if (ymnogit)
              {
                  decimal del = Convert.ToDecimal(textBox1.Tag) * Convert.ToDecimal(textBox1.Text);
                  textBox1.Text = del.ToString();
              }
              if (delenie)
              {
                  decimal del = Convert.ToDecimal(textBox1.Tag) / Convert.ToDecimal(textBox1.Text);
                  textBox1.Text = del.ToString();
              }
          }
     }
}