Tk::Error: Illegal division by zero at C:\perl\dwnspd.pl line 79.
 main::__ANON__ at C:\perl\dwnspd.pl line 79
 Tk callback for .button
 Tk::__ANON__ at C:/Strawberry/perl/site/lib/Tk.pm line 251
 Tk::Button::butUp at C:/Strawberry/perl/site/lib/Tk/Button.pm line 175
 <ButtonRelease-1>
 (command bound to event)