Well, let's see here. "Got to go" means have to go, "I've got a pen", means I have a pen, even worse "should have gotten" means should have got or any other number of 'should have .....' -- the list goes on and on. The point is two-fold : 1. anytime you use the verb "get" when it doesn't mean obtain or receive, ESPECIALLY with new English learners( come on we're supposed to be English teachers here!), either it is an idiom like "I get it" or it has a better rendering. 2. Check a Cambridge dictionary - (one written by the British) my bet is you will not find "gotten" anywhere in it. Let's not forget that American English has been somewhat 'Wild Wested' and many expressions mean something that have nothing to do with the literal meaning. Just check all the meanings of "get" in the American dictionary, there's at least 20 - JUST REMEMBER THIS CAN BE VERY CONFUSING FOR NEW LEARNERS.

> Aaaahhh, this was a major discussion provoker on Dave's Korean board
> a week or two ago.

> I for one use and teach "got" and will fight almost to the
> death for the sake of got.

> Re. "gotten," it is the American English past participle of
> got, whereas Australia, NZ and English use the more modern
> "got" so depending on who and where I'm teaching I use
> whichever is more correct.

> Got to go, I have to apply exams (my favorite part of the semester,
> he he he.)