I came across phrases like this:
I haven't read it, but a lot of 130s students love it.
Most of my exposure to this book comes from tutoring and grading for 161
which are just a little hard to swallow for an average 257 student
Are these numbers some sort of American class system or what is the meaning of them?
EDIT: I found this here. I am not familiar with the US education system, sorry I can’t bring more information. I am confused by this number system.