Couldn't you say getting numbers from other caches and putting them into a formula and getting an answer is solving a problem which is a Puzzle?

The cat is now out of the bag........

What about Letterbox caches where the co-ordinates is where the cache is actually sited (I'm guilty of this, I ran out of time). Surely the idea for a letterbox is that you follow directions (not sets of co-ordinates like a multi) from a known starting point to find the cache and you can stamp your 'book' when you found it, like Lair of the Lost Boys