Dropsums is a mathematical puzzle game for all ages which exercises your grey matter, great for keeping the brain cells sharp.

The game is also designed to benefit 7 to 11 year-olds (2nd grade to 5th grade in the U.S., Key Stage 2 in the U.K.) by supporting learning about mathematical expressions, the order of mathematical operations (as embodied in the BODMAS acronym), and simple algebra. There's also a game mode for practising times tables.

Extra game modes are available for a harder challenge, or for playing against the clock.