It's a $60 donation to the NBOME in exchange for a +/- 150 ballpark for your potential score. Also, a way to get accustomed to the poorly worded questions you'll see on exam day.
I don't think even the NBOME knows the answer key... my best suggestion would be to take it untimed and screen shot or write down the questions, and look them up later.
It's not like you know what you get wrong anyway to be able to accurately evaluate your performance.
it's a $60 donation to the nbome in exchange for a +/- 150 ballpark for your potential score. Also, a way to get accustomed to the poorly worded questions you'll see on exam day.