<p>I can get one for half price but I can't find the newest edition ISBN on any text book sites..</p>
<p>depends on the class. its not like the professor is going to check or even care if you get a text book. However, in some classes, the teachers use problem sets in the book as homework, which would be problematic.</p>
<p>As a college instructor, I would suggest you buy the correct edition. I know books are expensive; however, it's really a pain when a student has the wrong edition--page numbers are different, and sometimes there are substantial changes from edition to edition.</p>
<p>try emailing the professor and asking, some will say older editions are fine.</p>