Could be so much better
Aside from the awful grammatical and spelling errors, there are numerous mis-referenced articles of the code book. Some of the questions of the pop quizzes do not pertain to the prior question despite being asked a particular detail of that question. I found this twice in just under 100 questions. I think it helps a person go through the code book if it’s something you haven’t done in a while or you need to brush up on your formula skills. Be sure to reference other sources for various questions that don’t see like they make sense. Clearly, come language of the code book is difficult to understand. But then there are questions in which the wording makes no sense at all. It feels like a Beta version that never got saw through to completion. The functionality of the app is so-so and could also use an update.