I don't know how to use extended I get WA in extend!

>in var you must write extended
  ex:
  var
  a:extended;
>but in the program you can not use in with for
 but outhers you can
  ex: repeat
      a:=a+1;
     until a=100000;
>you must not use it in array
      eror ex:
          c:array[1..1000] of extended;