Great to exercise Memory and Math Skills, all ages. To play select a Base number, then tap start. Tap three numbered tiles so that the sum of the numbers equals a number that is a multiple of the Base number ( i.e. With a base of 9 tiles must add up to 9, 18, 27, 36, 45, 54, 63, 72, 81). Then the sum will be added to the score. Get the most points in one minute.