This would be a nice tool for math teachers who are introducing their students to statistics; it's also helpful for doing division in your head and keeping a running tab, so I could totally see this being at home in something akin to Brain Age. Not my cup of tea, but you did a great job with the logic! I did find one bug I'd like to report, too: when I was on the lowest introductory level and passed it, the option to proceed to the next level of difficulty wouldn't register when clicked.
Keep up the great work! Cheers!