#!/usr/bin/perl
use strict;
use warnings;
use Tie::File::Custom;

tie *fh, 'Tie::File::Custom', 'num.dat' or die "Unable to tie : $!";
(tied *fh)->NL( "\n\\d+\n" ); # Lines with numbers by themselves are record terminators

while ( <fh> ) {
    (tied *fh)->CHOMP( $_ );
    print "$_\n";
}