Keep Prime Numbers

Remove all the blocks to make the composite number going out but keep the prime number. Click or tap the unused block to drop the composite numbers.

Click on the blocks that are non-prime to clear them from the grid. Do not select the prime numbers as they must stay on the board. Utilize your knowledge of prime and composite numbers to carefully choose which blocks to eliminate. Advance by removing all composite numbers from each round. Be mindful of the increasing difficulty as you advance through the stages. Practice your number recognition to improve your score.