Chemistry Test

I took my chemistry midterm on Friday and I was stuck on the last problem for a while. I tried a bunch of different ways but I couldn't get a right answer. I finally figured it out and started writing it out but then the proctor called time. I wrote out everything except the last step and the final answer and he came and took my test. Turns out that if I had been able to finish that problem I would have gotten the highest grade in the class. Oh well, I got a good grade regardless.