Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click 
          Dim stri() As String = TextBox1.Text.Split("+") 
          Dim length_stri As Integer = stri.Length() 
          Dim i As Integer 
          Dim result As Double 
          For i = 1 To length_stri 
              Dim temp As String = stri(i - 1) 
              result = Val(temp) + Val(stri) 
          Next 
          Me.Text = result.ToString() 
      End Sub 
    End Class