Verify Answer button funtionality and keeping track of number correct and incorrect

ElementaryMathematics/Form1.Designer.cs

@@ -218,6 +218,7 @@
             this.btnChkAnswer.TabIndex = 6;
             this.btnChkAnswer.Text = "Check Answer";
             this.btnChkAnswer.UseVisualStyleBackColor = true;
+            this.btnChkAnswer.Click += new System.EventHandler(this.btnChkAnswer_Click);
             // 
             // lblMessage
             // 
@@ -251,6 +252,7 @@
             this.txtC.Name = "txtC";
             this.txtC.Size = new System.Drawing.Size(79, 20);
             this.txtC.TabIndex = 2;
+            this.txtC.TextChanged += new System.EventHandler(this.txtC_TextChanged);
             // 
             // txtB
             // 
@@ -258,6 +260,7 @@
             this.txtB.Name = "txtB";
             this.txtB.Size = new System.Drawing.Size(79, 20);
             this.txtB.TabIndex = 1;
+            this.txtB.TextChanged += new System.EventHandler(this.txtB_TextChanged);
             // 
             // txtA
             // 
@@ -265,6 +268,7 @@
             this.txtA.Name = "txtA";
             this.txtA.Size = new System.Drawing.Size(79, 20);
             this.txtA.TabIndex = 0;
+            this.txtA.TextChanged += new System.EventHandler(this.txtA_TextChanged);
             // 
             // chkShowSummary
             // 

ElementaryMathematics/Form1.cs

@@ -19,6 +19,11 @@ namespace ElementaryMathematics
         private bool isMultiply = false;
         private bool isDivide = false;
 
+        private Int32 numRunningCorrect = 0;
+        private Int32 numRunningIncorrect = 0;
+        
+        
+        
         public Form1()
         {
             InitializeComponent();
@@ -102,5 +107,147 @@ namespace ElementaryMathematics
         {
             Close();
         }
+
+        private ErrorProvider ep1 = new ErrorProvider();
+
+        private decimal Calculate(decimal a, decimal b, decimal c)
+        {
+
+            decimal answer = 0;
+
+
+            try
+            {
+
+                if (isAdd)
+                {
+                    answer = a + b;
+                }else if (isSubtract)
+                {
+                    answer = a - b;
+                }else if (isMultiply)
+                {
+                    answer = a * b;
+                }else if (isDivide)
+                {
+                    answer = a / b;
+                }
+                else
+                {
+                    throw new Exception();
+                }
+                
+            }
+            catch (Exception e)
+            {
+                MessageBox.Show("Whoops!");
+            }
+            
+
+            return answer;
+        }
+
+        private void Win()
+        {
+            
+            lblMessage.Text = "Good Job!";
+            numRunningCorrect++;
+            
+        }
+
+        private void Fail()
+        {
+
+            lblMessage.Text = "Try Again";
+            numRunningIncorrect++;
+            
+        }
+        
+        
+        private void btnChkAnswer_Click(object sender, EventArgs e)
+        {
+            
+            ep1.Clear();
+
+            decimal a = 0;
+            decimal b = 0;
+            decimal c = 0;
+
+            try
+            {
+
+                a = decimal.Parse(txtA.Text);
+
+                try
+                {
+
+                    b = decimal.Parse(txtB.Text);
+
+                    try
+                    {
+
+                        c = decimal.Parse(txtC.Text);
+
+                        try
+                        {
+
+                            if (c == Calculate(a,b,c))
+                            {
+
+                                Win();
+                                
+                            }
+                            else
+                            {
+                                Fail();
+                            }
+
+                        }
+                        catch (Exception exception)
+                        {
+                            ep1.SetError(btnChkAnswer, "Calculation Error");
+                        }
+                        
+
+                    }
+                    catch (Exception exception)
+                    {
+                        
+                        ep1.SetError(txtC, "Invalid Value");
+                        
+                    }
+                    
+                }
+                catch (Exception exception)
+                {
+                    
+                    ep1.SetError(txtB, "Invalid Value");
+                    
+                }
+                
+            }
+            catch (Exception exception)
+            {
+                
+                ep1.SetError(txtA, "Invalid Value");
+                
+            }
+            
+        }
+
+        private void txtA_TextChanged(object sender, EventArgs e)
+        {
+            ep1.Clear();
+        }
+
+        private void txtB_TextChanged(object sender, EventArgs e)
+        {
+            ep1.Clear();
+        }
+
+        private void txtC_TextChanged(object sender, EventArgs e)
+        {
+            ep1.Clear();
+        }
     }
 }