Here are some notes for the CBIT 2373 class on handling multiple click events in one event handler -

Private m_nFirstValue As Decimal = -1
Private m_nSecondValue As Decimal = -1

Private Sub ButtonAny_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click, Button2.Click, Button3.Click, Button4.Click, Button5.Click, Button6.Click, Button7.Click, Button8.Click, Button9.Click, Button12.Click
      txtResult.Text &= CType(sender, Button).Text
End Sub

Private Sub btnPlus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPlus.Click
      m_nFirstValue = CType(txtResult.Text, Decimal)
      txtResult.Text = ""
End Sub

Private Sub btnEquals_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEquals.Click
      m_nSecondValue = CType(txtResult.Text, Decimal)
      txtResult.Text = m_nFirstValue + m_nSecondValue
End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
      txtResult.Text = ""
      m_nFirstValue = -1
      m_nSecondValue = -1
End Sub