"So I went into the series with the intent to work every single problem. That turned out to be unrealistically ambitious" <-- that's how I felt about the book "Concrete Math". As an undergrad, I took Concrete Math as an elective. I could have taken is Pass/Fail (in which it wouldn't have counted towards my GPA), but I took it as a graded class. Fascinating stuff, and I really enjoyed it (still have the book on my shelf), but that class bloodied me up.