MaTris is a nice program for practicing the basic operations of arithmetic. The calculation method is preselectable. It includes simple counting exercises, addition with symbols, addition/subtraction with different number ranges, and multiplication/division with defined factors. One can thus train different learning skills. A solution button shows the correct result; optional sound effects provide audio feedback. After solution of a predefined number or time of exercises, the child may play a tetris-like game. The more exercises solved, the more points will be received in the game part. Multilingual version: German, English, Swedish, Italian, Spanish, French, Norwegian.