This app is addictive! Once you make one wrong click, you feel like you need to 'prove yourself' and get it right! Then, once you complete a section, you may look at your time and think: "I can do better than that!" And try to better your time. Eventually you have the test just memorized. You may think you'd get bored with it, but the creators of the app are constantly coming out with new sections for the test. Then, once you've completed it, it is, as someone previously mentioned, a lot of fun to hand your iPod or iPad or iPhone over to your friend and have them try. Once they fail, they'll be more than determined to be better than you at it!