My brother in law is currently working on taking his PRAXIS exams before student teaching. There was one on there for the PRAXIS1 Exam for both iPad and iPhone. There are 500 questions in Math, Reading, and Writing. Once it ask you a question, and you have answered it successfully, it will not show you that question again until you go through the entire question bank. You can use it in a study or exam mode. It does NOT use data! Hopefully one of your friends can use this app!
Here is the link for Apps Gone Free!
I am also starting a course from Stanford today called "How to Learn Math". It is a FREE course from Stanford for teachers that talks about Math and Growth Mindset, Conceptual Learning, Challenges, etc. I am so excited about this course. It is an online course that runs from today until the end of September, but all of the classes will be released by the end of July so you can finish in time for back to school! This will be my first class since my undergrad, and I am looking at starting my Masters next fall so I am nervous. You do not get any Grad School credit, but some schools are allowing professional development credit. I am doing it for myself and for my students so that I can become a better teacher. If you are interested, check it out it's not too late! They are also creating one for students that will be released this fall.