start:
   local
       number r;   
   end;
   [print "Radius? "];
   r = [ read ];
   [print "Circle Surface = "];
   [write [ surf r ]];
   [print "\n"];
end;

pi100 -> number:
   return 314;
end;

surf number r -> number:
   return ([ pi100 ] * r * r) / 100;
end;