Sub dateken()
Columns("D:D").NumberFormat = "General"
Columns("D:D").Replace What:="-", Replacement:="/", LookAt:=xlPart, _
SearchOrder:=xlByRows, MatchCase:=False
For n = 1 To Range("D65536").End(xlUp).Row
Range("D" & n) = CDate(Range("D" & n))
Next n
End Sub