oracle pagination query rownum

1SELECT * FROM (
2    SELECT a.*, rownum rn
3    FROM (
4        SELECT * FROM ORDERS WHERE CustomerID LIKE 'A%'
5        ORDER BY OrderDate DESC, ShippingDate DESC
6    ) a
7    WHERE rownum < ((pageNumber * pageSize) + 1 )
8)
9WHERE rn >= (((pageNumber-1) * pageSize) + 1);