Rack up points as you try to make prime numbers using dominoes. Use your mouse to play this addition game where the goal is to create sums that are prime, with an extra bonus if you can make a sum of 23. The top numbers are added together separately from the bottom numbers, so each domino you play will add to two different numbers. You can rotate each domino and you get to draw new dominoes ten times. If you reach a sum of 23 three times, you get another draw. Zeros and sums greater than 23 reset the tally. This game is strangely addicting once you get the hang of it.