I am using something like your keycalc sub now, although there are two problems. First, using $key[$_] as the destination confuses $key[$_-1]. The main problem is the use of ... ^ 5. I have tried this before and it gives me an error. Quoting '5' however does execute. Will this work? I do not know how perl actually handles strings so I do not know if this will give me the result I am looking for,