getting the last N tuples of a query

Hi!

if a want the first   5,10,N tuples  of a query  (even without order)
i just  have to do a:
select  * from table limit 10;


but, What can i do to get the last  10 tuples ???
  i try to do:
select * from table limit -10;  :-D  but  that query  return 0 tuples .

So, what is the right way to do that  with no order????