What is an ISBN?

The ISBN (International Standard Book Number) is a 10 or 13 digit code that uniquely identifies each edition of every textbook ever written. When professors assign books to their students, the ISBN of the assigned books is often provided to the students or the bookstore in order to make sure that everyone purchases the same edition.

How to use the number to get cheaper textbooks.

Because the ISBN is the standard identifier for all textbooks, students can actually search for the 10 or 13 digit ISBN of their college books on websites that allow you to sell and buy textbooks in order to look up the exact edition that their professors assigned. Instead of typing in the title, author and edition number on websites like SlugBooks, all you have to do is type in the ISBN and these sites automatically know the exact edition of the textbook you need.

Where do I find the number?

You can either find the ISBN on the course syllabus or the schedule of classes, or if you are in the bookstore, the ISBN is located below or above the barcode outside every book, but also appears on the copyright page right inside the book. The 13 digit number often starts with the numbers 978, while the ten digit number (less common) usually starts with a 0, 1 or 2.

The Ultimate ISBN Trick: Find an Older or International Edition

Using the information about the required course materials, look up the books you need and find out if there is an older edition, then ask the instructor if it's ok. Because older editions are always cheaper, these could be the most lucrative emails you will ever send in college. The exception to this rule is if you find a book that is an international edition of your assigned textbook, there's no need to ask the professor for permission. It's the same book! While professors will assign a set of specific editions to their classes, it is often worthwhile to contact the professor and ask if an older edition of the textbook is acceptable. This strategy is far more effective if you have searched for the ISBN, discovered the ISBN of an earlier edition, and specifically referenced that edition when emailing the professor. Here's a sample email template for a student that wants to professionally reach out to their professor to understand if an earlier edition is ok. Fill in the blanks, send the e-mail, and you will be in great shape.

Dear Professor [last name],

I am enrolled in your [class title] class this [Fall/Winter/Spring]. I noticed that you have assigned [Book Title], which is the [edition number] edition. I noticed that the earlier edition of this book is considerably less expensive: [include link to earlier edition of the book]. I wanted to understand if the specific edition you assigned is mandatory, or if it would be ok if I purchased the more affordable older edition.

Thank you for your time, I'm looking forward to being in this class!
[Your Name]
[Your Email]

A side-benefit of e-mailing your course’s professor (outside of potentially saving money when they tell you that it is okay to purchase earlier editions), is that the professor will see your name and recognize it next time you ask for help or show up at office hours. It always helps to show your instructors that you are trying hard.

Using ISBNs to Sell Books.

Using ISBNs to sell college books. Knowing the International Standard Book Number is also the easiest way to get the most money when you are selling your books! When you sell your cheap used books back to the bookstore, they're scanning the ISBN and seeing what they can offer. You can beat them at that game by searching for the ISBN on Amazon and seeing what other sellers are quoted at, and price your book close to these prices instead.

ISBNs and the library!

The ISBN also works at the library! This can be a huge time and money saver – instead of searching by title and potentially ending up with the wrong book, search by ISBN and beat your other classmates to reserving the books! Many college libraries offer copies of used textbooks on reserve, meaning that a few copies are available for students to check out in short rental periods (of 2-4 hours). Often times if you are able to take out a reserve textbook within a few hours of the library’s closing time, you can keep it for the night and return it the next morning.

Compare Prices by ISBN

SlugBooks allows you to search for college books by ISBN, but we also allow searching by course. We organize the ISBNs you need on pages for each specific course, so that you can see all of your books at once, instead of having to look them up individually.