use warnings;
use strict;

my %lines;
while (<DATA>) {
    my ($num) = $_ =~ /(\d+)$/;
    $lines{$num} = $_;
}
for (sort {$a <=> $b} keys %lines) {
    print $lines{$_};
}

__DATA__
foo bar 4
goo 1
hoo boo boo 2
yeah 3