Depends on whether I know how to do the problem or not.
In my first college math course, people within a couple points of an 'A' had a chance to raise their grade by solving a problem in front of the class that the professor chose. Naturally, the problems hadn't been something covered in class, but close enough that we might be able to see how we could extend what we'd learned to cover these new problems. Seeing as how these would be tough for us to see the link between these problems and what we'd covered, we could get up to three chances and only have to solve one (how many chances we got depended on how successful the others were - if the first couldn't solve his problem then the next got a chance at his, plus kept his own chance, and so on with the order rotating each day).
Three of us took him up on the offer and it is a very uncomfortable feeling to stand up in front of the class, write the problem on the board as he gives it, and to realize you don't have a clue where to start. And making a start and then realizing you were heading down a dead end just makes you even more uncomfortable. None of us were able to solve the first day's problem. We just looked clueless.
I was up first on the second day, which was a little cruel. If I'd realized the other two guys were going to just accept a 'B' rather than stand clueless in front of the class, I probably would have backed out too. As it was, I fumbled unsuccessfully with the problem just as I had the first day.
The third day, the other two guys backed out again. The only reason I went through with a final attempt on the third day was because I knew I'd only have to do this once more regardless of whether I succeeded or failed. The third day's problem was as bad as the first two, but looking at it, I suddenly realized an approach that really should work - and it did!
The other two guys were a little bummed out. One could have solved the second day's problem and the other could have solved the third day's problem (and he would have first chance at the third day's problem - I would have been shut out).
Kind of a fun little game for the professor, and maybe even for the rest of the students to watch, but a pretty nerve wracking game to actually play.
