use POSIX 'ceil';

sub tape_label {
    my $len = shift() + 1; ## simpler since we'll start at 0  

    my @cols;
    my $n_cols = ceil( log($len) / log(10) );

    for my $log (0 .. $n_cols-1) {
      my $pad     = 10**$log - 1;
      my $pattern = join( " " x $pad, 0 .. 9, "" );

      unshift @cols, substr( $pattern x ceil($len/10**$log), 0, $len );
    }

    return @cols;
}