I have an ever-growing series of videos on YouTube. These cover some of the material in the book in a different way, so even if you have read the book, you should check these out.
Some readers may not competely understand the Luhn algorithm from the descripton in the book; here's an expanded explation.
Instructor's Exercise Guide
If you are using, or are considering using, Think Like a Programmer in a class or lab, please contact me (firstname.lastname@example.org) for a copy of the instructor's exercise guide. In this guide, I offer suggestions for coaching students through the problem solving of most of the exercises -- without giving away too much, so that the student is still the one solving the problem.
Although this guide contains no answers to exercises, it does offer a lot of hints that could shortcut the problem-solving process, so please do not contact me for the guide if you are a student in a course using my text; ask your instructor or lab assistant for help, and encourage them to ask me for the guide if they don't have it already.