use warnings;
use diagnostics;
use strict;
my @array = ("8.foo", "6.bar", "7.baz", 
"5.biz", "3.fizzle", "0.fro", "9.boz");

print join "\n",
map {$_->[0]}
sort {$a->[1] <=> $b->[1]}
map { [$_, by_number($_)] } @array;

sub by_number {
        my $value = shift;
        if ($value =~ m/^(\d+)/) {
                return $1
        }
}