From BrainSpeeder Brain Training:
Online brain training and brain teasers for free! Mind exercises and mental workout for your grey matter with big fun factor. The quick brain games of BrainSpeeder enhance your mental agility with different types of mind games such as Arithmetic, Mnemonic, Speedoku and so on. This brain trainer will pep up your mind: ... Solve at top speed a series of math equations by mental arithmetic. The game Mnemonic flashes numbers or numerical series at the player, which he has to reproduce correctly and as quick as possible. In the style of Sudoku, Speedoku asks the player to complete numerical series. The missing number has to be recognized and typed in as fast as possible. But what sounds easy enough at the beginning will challenge the player after a few rounds: A refined online league system and the "Hall of Brain" allow him to match himself with other players worldwide. Only the player who solves his tasks correctly (and quickly, above all) can ascend to the next league at the end of the week. Furthermore, a "Brain of the Day" will be nominated daily. Cup ties offer opportunities to compete with others in two-party teams in a sudden death-system. If you want to resist the allurement of online-gaming, you can still keep your brain cells fit and play the brain games of BrainSpeeder on your home computer without an Internet connection as well. Have fun and train your brain - just be quicker!