Private Sub Verbrauch_berechnen()
  Dim Stand As Double
 
  For Zeile As Integer = 0 To DGVStrom.Rows.Count - 1
    If Zeile = 0 Then
      DGVStrom.Rows(Zeile).Cells(5).Value = "erste Ablesung"
      Stand = DGVStrom.Rows(Zeile).Cells(4).Value
    Else
      DGVStrom.Rows(Zeile).Cells(5).Value = DGVStrom.Rows(Zeile).Cells(4).Value _
        - Stand
      Stand = DGVStrom.Rows(Zeile).Cells(4).Value
    End If
  Next Zeile
End Sub