SQL> declare
  2  pi number:=3.142;
  3  r number;
  4  a number;
  5  procedure area(x in number,y in number,z out number)
  6  as
  7  begin
  8  z:=x*y*y;
  9  end;
 10  begin
 11  r:=3;
 12  area(pi,r,a);
 13  dbms_output.put_line('area is : '||a);
 14  end;

area is : 28.278                                                                

PL/SQL procedure successfully completed.