I am working through the first chapter of Principles of Mathematical Analysis and I am wondering how many of the twenty exercise problems I should do. I think the first ten are very to moderately easy (with 7 as an exception), but the next ten are much more difficult. I am of course trying to do all of them, but how many should I be content with doing successfully? Also, how many of the exercises would a college course using the book require? I am not trying to "get out of work" as I am doing this independently anyway, I just want to know what you would recommend.