newbe to the forums but been playing for some time (level 72) no short cuts. How many locations can I discover? So far I'm at 331.

I believe gamesas said (at some point) that there are 250 major locations and 350 minor locations. I'm not sure what counts as major and what counts as minor but this gives you a rough idea. Personally, even my most extensive play-throughs (level 95-ish) didn't cover all that. You should keep going and post your finally tally.

Also - don't forget all the stuff the Dawnguard and Dragonborn DLCs add. The Soul Cairn and Forgotten Vale are quite large in their own rights.

On my old file, I discovered 508.