13 of 13. Our standards must be going down. Way down.
Math was always tough for me. I never did figure out what Calculus is. Course it could be because I went to class exactly twice.
My wife is the same way. Then, just yesterday morning, she discovered Calculus all on her own. We were bemoaning that it is darker in the morning when the alarm goes off. She observed that not only that, but that it seemed to be changing more rapidly day-to-day.
I explained that she was correct and that was the first derivative that she had observed. I think she gets it a little bit better now.