use List::Util qw( sum );

my $id = (sum map ord, map /./sg, $word) % 65536;

##</code><code>##

my $id = 0;
foreach (map ord, map /./sg, $word) {
   $id = ($id + $_) % 65536;
}

##</code><code>##

use Digest::MD5 qw( md5 );

my $id = unpack('n', substr(md5($word), -2));