Kalculate is a you vs. the Internet style game for math lovers. The rules are simple: answer as many math problems as you can in 90 seconds. At the end of each round, Kalculate will tally up all the scores and show you where you ranked relative to others currently playing.

Tip: answering 3 questions in 10 seconds earns you a score multiplier

If you prefer to just practice and stay out of the competition, there's an offline mode that allows you to play solo.

Kalculate is free (ad-supported) and can be downloaded here.