You really don't need to care if perl stores your numbers as strings or numbers. Perl will convert as necessary and it all just works!

Consider:

my $str = '123';
$str += 10;
print "str = /$str/\n";

my $num = 456;
$num =~ s/6/8/;
print "num = /$num/\n";
[download]

Output:

str = /133/
num = /458/
[download]