Hashes are inherently unsorted, so let's seperate combining the hashes from sorting and printing them:

#!/usr/bin/perl -w
use strict;

my %hash1 = qw( 2 cars 1 motorcycle 4 balloons );
my %hash2 = qw( 5 airplanes 3 helicopters 6 skateboards );
# combine
my %hash = (%hash1, %hash2);
# print sorted
print map "$_ $hash{$_}\n", sort {$a<=>$b} keys %hash;
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If you need the sorted keys for more than the print, you could save them in an array of their own.

After Compline,
Zaxo