I learned to use the TI-89 in an android emulator, last year, and I find it more useful than the ad-filled native Android apps available as an alternative. The

I learned to use the TI-89 in an android emulator, last year, and I find it more useful than the ad-filled native Android apps available as an alternative. The thing solves symbolic matrix equations like it's nothing. Awesome investment, and zero money spent.