Private Sub Worksheet_Change(ByVal zz As Range)
Dim x As String
If zz.Column < 3 Or zz.Column > 4 Then Exit Sub
If zz.Row < 2 Or zz.Row > 300 Then Exit Sub
Application.EnableEvents = False
If zz.Column = 4 Then
x = Format(zz, "0000")
zz.Value = Left(x, 2) & ":" & Right(x, 2)
Else
x = Format(zz, "00000000")
zz.Value = Left(x, 2) & "/" & Mid(x, 3, 2) & "/" & Right(x, 4)
End If
Application.EnableEvents = True
End Sub