And the question is?

I hope it's not

So here 6.66 would be returned?

But you're not asking us to do your homework, are you? If not, as we all hope, what have you tried thus far? Which is your code?

Said this, it's not entirely clear to me whether you want uniq numbers per file or amongst all files. Whatever, you may have guessed that this kind of questions gets asked quite frequently, and indeed there's at least a faq that should be of considerable interest to you: check perldoc -q unique.

Also, you may have done a search here (or a Super Search); in particular a question with a subject nearly identical to yours has been asked quite recently.