namespace Calculator
{
   /// <summary>
   /// Summary description for Form1.
   /// </summary>
   public class Form1 : System.Windows.Forms.Form
   {
      double store=0;
      double result=0;
      string input="";
      double memory=0;
      bool newNumber=true;
      
      string operation="";
      private System.Windows.Forms.MainMenu mainMenu1;
      private System.Windows.Forms.MenuItem menuItem4;
      private System.Windows.Forms.MenuItem menuItem5;
      private System.Windows.Forms.MenuItem menuItem6;
      private System.Windows.Forms.MenuItem Edit;
      private System.Windows.Forms.MenuItem EditCopy;
      private System.Windows.Forms.MenuItem EditPaste;
      private System.Windows.Forms.Button btnBkSpc;
      private System.Windows.Forms.Label lblMemory;
      private System.Windows.Forms.Button btnC;
      private System.Windows.Forms.Button btnCE;
      private System.Windows.Forms.Button btnMC;
      private System.Windows.Forms.Button btnMR;
      private System.Windows.Forms.Button btnMS;
      private System.Windows.Forms.Button btnM;
      private System.Windows.Forms.Button btn1;
      private System.Windows.Forms.Button btn2;
      private System.Windows.Forms.Button btn3;
      private System.Windows.Forms.Button btn4;
      private System.Windows.Forms.Button btn5;
      private System.Windows.Forms.Button btn6;
      private System.Windows.Forms.Button btn7;
      private System.Windows.Forms.Button btn8;
      private System.Windows.Forms.Button btn9;
      private System.Windows.Forms.Button btn0;
      private System.Windows.Forms.Button btnAddSubt;
      private System.Windows.Forms.Button btnDot;
      private System.Windows.Forms.Button btnAdd;
      private System.Windows.Forms.Button btnSqrt;
      private System.Windows.Forms.Button btnSubtract;
      private System.Windows.Forms.Button btnSq;
      private System.Windows.Forms.Button btnMultiply;
      private System.Windows.Forms.Button btnExpo;
      private System.Windows.Forms.Button btnDivide;
      private System.Windows.Forms.Button btnEqual;
      private System.Windows.Forms.TextBox txtDisplay;
      /// <summary>
      /// Required designer variable.
      /// </summary>
      private System.ComponentModel.Container components = null;

      public Form1()
      {
         //
         // Required for Windows Form Designer support
         //
         InitializeComponent();

         //
         // TODO: Add any constructor code after InitializeComponent call
         //
      }

      /// <summary>
      /// Clean up any resources being used.
      /// </summary>
      protected override void Dispose( bool disposing )
      {
         if( disposing )
         {
            if (components != null)
            {
               components.Dispose();
            }
         }
         base.Dispose( disposing );
      }

      #region Windows Form Designer generated code
      /// <summary>
      /// Required method for Designer support - do not modify
      /// the contents of this method with the code editor.
      /// </summary>
      private void InitializeComponent()
      {
         this.mainMenu1 = new System.Windows.Forms.MainMenu();
         this.Edit = new System.Windows.Forms.MenuItem();
         this.EditCopy = new System.Windows.Forms.MenuItem();
         this.EditPaste = new System.Windows.Forms.MenuItem();
         this.menuItem4 = new System.Windows.Forms.MenuItem();
         this.menuItem5 = new System.Windows.Forms.MenuItem();
         this.menuItem6 = new System.Windows.Forms.MenuItem();
         this.btnBkSpc = new System.Windows.Forms.Button();
         this.lblMemory = new System.Windows.Forms.Label();
         this.btnC = new System.Windows.Forms.Button();
         this.btnCE = new System.Windows.Forms.Button();
         this.btnMC = new System.Windows.Forms.Button();
         this.btnMR = new System.Windows.Forms.Button();
         this.btnMS = new System.Windows.Forms.Button();
         this.btnM = new System.Windows.Forms.Button();
         this.btn1 = new System.Windows.Forms.Button();
         this.btn2 = new System.Windows.Forms.Button();
         this.btn3 = new System.Windows.Forms.Button();
         this.btn4 = new System.Windows.Forms.Button();
         this.btn5 = new System.Windows.Forms.Button();
         this.btn6 = new System.Windows.Forms.Button();
         this.btn7 = new System.Windows.Forms.Button();
         this.btn8 = new System.Windows.Forms.Button();
         this.btn9 = new System.Windows.Forms.Button();
         this.btn0 = new System.Windows.Forms.Button();
         this.btnAddSubt = new System.Windows.Forms.Button();
         this.btnDot = new System.Windows.Forms.Button();
         this.btnAdd = new System.Windows.Forms.Button();
         this.btnSqrt = new System.Windows.Forms.Button();
         this.btnSubtract = new System.Windows.Forms.Button();
         this.btnSq = new System.Windows.Forms.Button();
         this.btnMultiply = new System.Windows.Forms.Button();
         this.btnExpo = new System.Windows.Forms.Button();
         this.btnDivide = new System.Windows.Forms.Button();
         this.btnEqual = new System.Windows.Forms.Button();
         this.txtDisplay = new System.Windows.Forms.TextBox();
         this.SuspendLayout();
         //
         // mainMenu1
         //
         this.mainMenu1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
                                                                                  this.Edit,
                                                                                  this.menuItem4});
         //
         // Edit
         //
         this.Edit.Index = 0;
         this.Edit.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
                                                                             this.EditCopy,
                                                                             this.EditPaste});
         this.Edit.Text = "&Edit";
         //
         // EditCopy
         //
         this.EditCopy.Checked = true;
         this.EditCopy.Index = 0;
         this.EditCopy.Shortcut = System.Windows.Forms.Shortcut.CtrlC;
         this.EditCopy.Text = "&Copy";
         //
         // EditPaste
         //
         this.EditPaste.Index = 1;
         this.EditPaste.Shortcut = System.Windows.Forms.Shortcut.CtrlV;
         this.EditPaste.Text = "&Paste";
         //
         // menuItem4
         //
         this.menuItem4.Index = 1;
         this.menuItem4.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
                                                                                  this.menuItem5,
                                                                                  this.menuItem6});
         this.menuItem4.Text = "&Help";
         //
         // menuItem5
         //
         this.menuItem5.Index = 0;
         this.menuItem5.Text = "&Help Topics";
         //
         // menuItem6
         //
         this.menuItem6.Index = 1;
         this.menuItem6.Text = "About Calculator";
         //
         // btnBkSpc
         //
         this.btnBkSpc.ForeColor = System.Drawing.Color.Black;
         this.btnBkSpc.Location = new System.Drawing.Point(56, 40);
         this.btnBkSpc.Name = "btnBkSpc";
         this.btnBkSpc.Size = new System.Drawing.Size(56, 23);
         this.btnBkSpc.TabIndex = 1;
         this.btnBkSpc.Text = "&Bk Spc";
         this.btnBkSpc.Click += new System.EventHandler(this.btnBkSpc_Click);
         this.btnBkSpc.KeyDown += new System.Windows.Forms.KeyEventHandler(this.btnBkSpc_KeyDown);
         //
         // lblMemory
         //
         this.lblMemory.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
         this.lblMemory.Location = new System.Drawing.Point(16, 40);
         this.lblMemory.Name = "lblMemory";
         this.lblMemory.Size = new System.Drawing.Size(32, 23);
         this.lblMemory.TabIndex = 2;
         //
         // btnC
         //
         this.btnC.Location = new System.Drawing.Point(120, 40);
         this.btnC.Name = "btnC";
         this.btnC.Size = new System.Drawing.Size(48, 23);
         this.btnC.TabIndex = 3;
         this.btnC.Text = "&C";
         this.btnC.Click += new System.EventHandler(this.btnC_Click);
         //
         // btnCE
         //
         this.btnCE.Location = new System.Drawing.Point(176, 40);
         this.btnCE.Name = "btnCE";
         this.btnCE.Size = new System.Drawing.Size(56, 23);
         this.btnCE.TabIndex = 4;
         this.btnCE.Text = "&CE";
         this.btnCE.Click += new System.EventHandler(this.btnCE_Click);
         //
         // btnMC
         //
         this.btnMC.Location = new System.Drawing.Point(16, 72);
         this.btnMC.Name = "btnMC";
         this.btnMC.Size = new System.Drawing.Size(32, 23);
         this.btnMC.TabIndex = 5;
         this.btnMC.Text = "MC";
         this.btnMC.Click += new System.EventHandler(this.btnMC_Click);
         //
         // btnMR
         //
         this.btnMR.Location = new System.Drawing.Point(16, 104);
         this.btnMR.Name = "btnMR";
         this.btnMR.Size = new System.Drawing.Size(32, 23);
         this.btnMR.TabIndex = 6;
         this.btnMR.Text = "MR";
         this.btnMR.Click += new System.EventHandler(this.btnMR_Click);
         //
         // btnMS
         //
         this.btnMS.Location = new System.Drawing.Point(16, 136);
         this.btnMS.Name = "btnMS";
         this.btnMS.Size = new System.Drawing.Size(32, 23);
         this.btnMS.TabIndex = 7;
         this.btnMS.Text = "MS";
         this.btnMS.Click += new System.EventHandler(this.btnMS_Click);
         //
         // btnM
         //
         this.btnM.Location = new System.Drawing.Point(16, 168);
         this.btnM.Name = "btnM";
         this.btnM.Size = new System.Drawing.Size(32, 23);
         this.btnM.TabIndex = 8;
         this.btnM.Text = "M+";
         this.btnM.Click += new System.EventHandler(this.btnM_Click);
         //
         // btn1
         //
         this.btn1.Location = new System.Drawing.Point(56, 72);
         this.btn1.Name = "btn1";
         this.btn1.Size = new System.Drawing.Size(32, 23);
         this.btn1.TabIndex = 9;
         this.btn1.Text = "&1";
         this.btn1.Click += new System.EventHandler(this.btn1_Click);
         //
         // btn2
         //
         this.btn2.Location = new System.Drawing.Point(88, 72);
         this.btn2.Name = "btn2";
         this.btn2.Size = new System.Drawing.Size(32, 23);
         this.btn2.TabIndex = 10;
         this.btn2.Text = "&2";
         this.btn2.Click += new System.EventHandler(this.btn2_Click);
         //
         // btn3
         //
         this.btn3.Location = new System.Drawing.Point(120, 72);
         this.btn3.Name = "btn3";
         this.btn3.Size = new System.Drawing.Size(32, 23);
         this.btn3.TabIndex = 11;
         this.btn3.Text = "&3";
         this.btn3.Click += new System.EventHandler(this.btn3_Click);
         //
         // btn4
         //
         this.btn4.Location = new System.Drawing.Point(56, 104);
         this.btn4.Name = "btn4";
         this.btn4.Size = new System.Drawing.Size(32, 23);
         this.btn4.TabIndex = 12;
         this.btn4.Text = "&4";
         this.btn4.Click += new System.EventHandler(this.btn4_Click);
         //
         // btn5
         //
         this.btn5.Location = new System.Drawing.Point(88, 104);
         this.btn5.Name = "btn5";
         this.btn5.Size = new System.Drawing.Size(32, 23);
         this.btn5.TabIndex = 13;
         this.btn5.Text = "&5";
         this.btn5.Click += new System.EventHandler(this.btn5_Click);
         //
         // btn6
         //
         this.btn6.Location = new System.Drawing.Point(120, 104);
         this.btn6.Name = "btn6";
         this.btn6.Size = new System.Drawing.Size(32, 23);
         this.btn6.TabIndex = 14;
         this.btn6.Text = "&6";
         this.btn6.Click += new System.EventHandler(this.btn6_Click);
         //
         // btn7
         //
         this.btn7.Location = new System.Drawing.Point(56, 136);
         this.btn7.Name = "btn7";
         this.btn7.Size = new System.Drawing.Size(32, 23);
         this.btn7.TabIndex = 15;
         this.btn7.Text = "&7";
         this.btn7.Click += new System.EventHandler(this.btn7_Click);
         //
         // btn8
         //
         this.btn8.Location = new System.Drawing.Point(88, 136);
         this.btn8.Name = "btn8";
         this.btn8.Size = new System.Drawing.Size(32, 23);
         this.btn8.TabIndex = 16;
         this.btn8.Text = "&8";
         this.btn8.Click += new System.EventHandler(this.btn8_Click);
         //
         // btn9
         //
         this.btn9.Location = new System.Drawing.Point(120, 136);
         this.btn9.Name = "btn9";
         this.btn9.Size = new System.Drawing.Size(32, 23);
         this.btn9.TabIndex = 17;
         this.btn9.Text = "&9";
         this.btn9.Click += new System.EventHandler(this.btn9_Click);
         //
         // btn0
         //
         this.btn0.Location = new System.Drawing.Point(56, 168);
         this.btn0.Name = "btn0";
         this.btn0.Size = new System.Drawing.Size(32, 23);
         this.btn0.TabIndex = 18;
         this.btn0.Text = "&0";
         this.btn0.Click += new System.EventHandler(this.btn0_Click);
         //
         // btnAddSubt
         //
         this.btnAddSubt.Location = new System.Drawing.Point(88, 168);
         this.btnAddSubt.Name = "btnAddSubt";
         this.btnAddSubt.Size = new System.Drawing.Size(32, 23);
         this.btnAddSubt.TabIndex = 19;
         this.btnAddSubt.Text = "+/-";
         //
         // btnDot
         //
         this.btnDot.Location = new System.Drawing.Point(120, 168);
         this.btnDot.Name = "btnDot";
         this.btnDot.Size = new System.Drawing.Size(32, 23);
         this.btnDot.TabIndex = 20;
         this.btnDot.Text = "&.";
         this.btnDot.Click += new System.EventHandler(this.btnDot_Click);
         //
         // btnAdd
         //
         this.btnAdd.Location = new System.Drawing.Point(168, 72);
         this.btnAdd.Name = "btnAdd";
         this.btnAdd.Size = new System.Drawing.Size(32, 23);
         this.btnAdd.TabIndex = 21;
         this.btnAdd.Text = "&+";
         this.btnAdd.Click += new System.EventHandler(this.btnAdd_Click);
         //
         // btnSqrt
         //
         this.btnSqrt.Location = new System.Drawing.Point(200, 72);
         this.btnSqrt.Name = "btnSqrt";
         this.btnSqrt.Size = new System.Drawing.Size(32, 23);
         this.btnSqrt.TabIndex = 22;
         this.btnSqrt.Text = "sqrt";
         this.btnSqrt.Click += new System.EventHandler(this.btnSqrt_Click);
         //
         // btnSubtract
         //
         this.btnSubtract.Location = new System.Drawing.Point(168, 104);
         this.btnSubtract.Name = "btnSubtract";
         this.btnSubtract.Size = new System.Drawing.Size(32, 23);
         this.btnSubtract.TabIndex = 23;
         this.btnSubtract.Text = "&-";
         this.btnSubtract.Click += new System.EventHandler(this.btnSubtract_Click);
         //
         // btnSq
         //
         this.btnSq.Location = new System.Drawing.Point(200, 104);
         this.btnSq.Name = "btnSq";
         this.btnSq.Size = new System.Drawing.Size(32, 23);
         this.btnSq.TabIndex = 24;
         this.btnSq.Text = "sq";
         this.btnSq.Click += new System.EventHandler(this.btnSq_Click);
         //
         // btnMultiply
         //
         this.btnMultiply.Location = new System.Drawing.Point(168, 136);
         this.btnMultiply.Name = "btnMultiply";
         this.btnMultiply.Size = new System.Drawing.Size(32, 23);
         this.btnMultiply.TabIndex = 25;
         this.btnMultiply.Text = "&*";
         this.btnMultiply.Click += new System.EventHandler(this.btnMultiply_Click);
         //
         // btnExpo
         //
         this.btnExpo.Location = new System.Drawing.Point(200, 136);
         this.btnExpo.Name = "btnExpo";
         this.btnExpo.Size = new System.Drawing.Size(32, 23);
         this.btnExpo.TabIndex = 26;
         this.btnExpo.Text = "1/x";
         this.btnExpo.Click += new System.EventHandler(this.btnExpo_Click);
         //
         // btnDivide
         //
         this.btnDivide.Location = new System.Drawing.Point(168, 168);
         this.btnDivide.Name = "btnDivide";
         this.btnDivide.Size = new System.Drawing.Size(32, 23);
         this.btnDivide.TabIndex = 27;
         this.btnDivide.Text = "&/";
         this.btnDivide.Click += new System.EventHandler(this.btnDivide_Click);
         //
         // btnEqual
         //
         this.btnEqual.Location = new System.Drawing.Point(200, 168);
         this.btnEqual.Name = "btnEqual";
         this.btnEqual.Size = new System.Drawing.Size(32, 23);
         this.btnEqual.TabIndex = 28;
         this.btnEqual.Text = "&=";
         this.btnEqual.Click += new System.EventHandler(this.btnEqual_Click);
         //
         // txtDisplay
         //
         this.txtDisplay.Location = new System.Drawing.Point(16, 8);
         this.txtDisplay.Name = "txtDisplay";
         this.txtDisplay.Size = new System.Drawing.Size(216, 20);
         this.txtDisplay.TabIndex = 29;
         this.txtDisplay.Text = "";
         this.txtDisplay.TextAlign = System.Windows.Forms.HorizontalAlignment.Right;
         //
         // Form1
         //
         this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
         this.ClientSize = new System.Drawing.Size(248, 209);
         this.Controls.Add(this.txtDisplay);
         this.Controls.Add(this.btnEqual);
         this.Controls.Add(this.btnDivide);
         this.Controls.Add(this.btnExpo);
         this.Controls.Add(this.btnMultiply);
         this.Controls.Add(this.btnSq);
         this.Controls.Add(this.btnSubtract);
         this.Controls.Add(this.btnSqrt);
         this.Controls.Add(this.btnAdd);
         this.Controls.Add(this.btnDot);
         this.Controls.Add(this.btnAddSubt);
         this.Controls.Add(this.btn0);
         this.Controls.Add(this.btn9);
         this.Controls.Add(this.btn8);
         this.Controls.Add(this.btn7);
         this.Controls.Add(this.btn6);
         this.Controls.Add(this.btn5);
         this.Controls.Add(this.btn4);
         this.Controls.Add(this.btn3);
         this.Controls.Add(this.btn2);
         this.Controls.Add(this.btn1);
         this.Controls.Add(this.btnM);
         this.Controls.Add(this.btnMS);
         this.Controls.Add(this.btnMR);
         this.Controls.Add(this.btnMC);
         this.Controls.Add(this.btnCE);
         this.Controls.Add(this.btnC);
         this.Controls.Add(this.lblMemory);
         this.Controls.Add(this.btnBkSpc);
         this.Menu = this.mainMenu1;
         this.Name = "Form1";
         this.Text = "Calculater";
         this.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.Form1_KeyPress);
         this.Load += new System.EventHandler(this.Form1_Load);
         this.ResumeLayout(false);

      }
      #endregion

      /// <summary>
      /// The main entry point for the application.
      /// </summary>
      [STAThread]
      static void Main()
      {
        
         Application.Run(new Form1());
      }

      private void Form1_Load(object sender, System.EventArgs e)
      {
        
      }

        

      private void btn1_Click(object sender, System.EventArgs e)
      {
         InputNumber("1");
        
      }

      private void btn2_Click(object sender, System.EventArgs e)
      {
         InputNumber("2");
        
      }

      private void btn3_Click(object sender, System.EventArgs e)
      {
         InputNumber("3");
        
      }

      private void btn4_Click(object sender, System.EventArgs e)
      {
         InputNumber("4");
      
      }

      private void btn5_Click(object sender, System.EventArgs e)
      {
         InputNumber("5");
        
      }

      private void btn6_Click(object sender, System.EventArgs e)
      {
         InputNumber("6");
        
      }

      private void btn7_Click(object sender, System.EventArgs e)
      {
         InputNumber("7");
        
      }

      private void btn8_Click(object sender, System.EventArgs e)
      {
         InputNumber("8");
        
      }

      private void btn9_Click(object sender, System.EventArgs e)
      {
         InputNumber("9");
        
      }

      private void btn0_Click(object sender, System.EventArgs e)
      {
         InputNumber("0");
      }
      private void btnDot_Click(object sender, System.EventArgs e)
      {
         InputNumber(".");
      }

      private void InputNumber(string input)
      {
         if(newNumber==true)
         {
            txtDisplay.Text=input;
         }
         else
         {
            txtDisplay.Text+=input;
         }
         newNumber=false;
      }
      private void btnC_Click(object sender, System.EventArgs e)
      {
         txtDisplay.Text="0";
         result=0;
         operation="";
        
      }
      private void btnAdd_Click(object sender, System.EventArgs e)
      {  
         OperationClicked("+");
        
      }

      private void btnSubtract_Click(object sender, System.EventArgs e)
      {
         OperationClicked("-");
      }

      private void btnMultiply_Click(object sender, System.EventArgs e)
      {
         OperationClicked("*");
      }

      private void btnDivide_Click(object sender, System.EventArgs e)
      {
         OperationClicked("/");

      }
      private void btnSqrt_Click(object sender, System.EventArgs e)
      {
         OperationClicked("sqrt");
      }

      private void btnSq_Click(object sender, System.EventArgs e)
      {
         OperationClicked("sq");
      }

      private void btnEqual_Click(object sender, System.EventArgs e)
      {
         performOperation();
      }

      
      private void OperationClicked(string op)
      {  newNumber=true;
         store = double.Parse( txtDisplay.Text);
          
         performOperation();
         operation = op;
        
      }
      

      private void performOperation()
      {
         double term2 = double.Parse(txtDisplay.Text);
         if(operation != "")
         {  
            

            switch(operation)
            {
                  
               case"+":
                  result=store+term2;
                  break;
               case"-":
                  result=store-term2;
                  break;
               case"*":
                  result=store*term2;
                  break;
               case"/":
                  result=store/term2;
                  break;
               case"sqrt":
                  result=Math.Sqrt(store);
                  break;
               case"sq":
                  result=store*store;
                  break;
               case"exp":
                  result=Math.Exp(store);
                  break;

            }
           txtDisplay.Text =  result.ToString();
        
         }
      }

      private void Form1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
      {
         char c = e.KeyChar;
         if(char.IsNumber©)
         {
            if(txtDisplay.Text== "0")
            {
               txtDisplay.Text = c.ToString();
            }
            else
            {
               txtDisplay.Text =  txtDisplay.Text+ c;
            }
         }

      }

      private void btnExpo_Click(object sender, System.EventArgs e)
      {
        
      }

      private void btnMC_Click(object sender, System.EventArgs e)
      {
         memory=0;
         txtDisplay.Text="";
         lblMemory.Text="";
        
      }

      private void btnMR_Click(object sender, System.EventArgs e)
      {
         txtDisplay.Text=memory.ToString();
      }

      private void btnMS_Click(object sender, System.EventArgs e)
      {
         memory=Double.Parse(txtDisplay.Text);
         txtDisplay.Text="";
         lblMemory.Text="M";
      }

      private void btnM_Click(object sender, System.EventArgs e)
      {
         memory+=double.Parse(txtDisplay.Text);
      }

      private void btnCE_Click(object sender, System.EventArgs e)
      {
         txtDisplay.Text="0";
      }

      

      private void btnBkSpc_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
      {
            switch(e.KeyData)
       {
          case Keys.Back:
             if(txtDisplay.Text.Length-1>=0)
             {
                txtDisplay.Text=txtDisplay.Text.Remove(txtDisplay.Text.Length-1,1);
             }
             break;
          case Keys.Enter:
             txtDisplay.Text=result.ToString();
             break;
       }
      
      }

      private void btnBkSpc_Click(object sender, System.EventArgs e)
      {
      
      }
   }
}

private void OperationClicked(string op) {
   newNumber = true;
   store = double.Parse(txtDisplay.Text);
...