Private Sub Worksheet_Change(ByVal Target As Range)
Dim rng As Range, h As Double
If Intersect(Range("D6"), Target) Is Nothing _
Or Target.Cells.Count > 1 _
Or Target.Value < 3 _
Or Target.Value > 173 Then Exit Sub
Set rng = Range(Rows(11), Rows(184))
With rng
.Hidden = False
.AutoFit
h = 480 / Target.Value
If h > ActiveSheet.StandardHeight Then _
.RowHeight = 480 / Target.Value
End With
rng.Resize(rng.Rows.Count - Int(Target.Value)).Hidden = True
End Sub