This is a great game to play with your children once they have a good knowledge of the 3x table. The idea of the game is to put four counters in a row, across, down or diagonally, and of course, stop the other player from doing so. Knowledge of the 3x table will help enormously. To put a counter on a square a number has to be typed in and then multiplied by 3. If it is not correct play goes to the second player without a counter being placed on the board. Calculator game: 3x table