johngg@shiraz:~/perl/Monks > perl -Mstrict -Mwarnings -E '
my @data = qw{
   this_5_string_12
   some_12_garbage_23
   this_5_string_8
   17
   this_5_string_23
   some_12_garbage_6
   102
   this_5_string_19
   5
   this_5_string_101
   };
my $width = 50;

say for
   map { substr $_, 54 }
   sort
   map { do {
            no warnings qw{ uninitialized };
            pack qq{NA${width}A*}, reverse( m{(.*\D)?(\d+)$} ), $_;
            }
       }
   @data;'
5
some_12_garbage_6
this_5_string_8
this_5_string_12
17
this_5_string_19
some_12_garbage_23
this_5_string_23
this_5_string_101
102