You are looking at a very old, but free version of the course. If you are interesed the most recent version, check it out on the Perl Maven site.
>perl examples/bc/bc1.pl bc 1.06 Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc. This is free software with ABSOLUTELY NO WARRANTY. For details type `warranty'. 30 Success