Keep Prime Numbers

Defend mathematical truth in Keep Prime Numbers, the number theory action-puzzle where composite invaders threaten the sanctity of prime numbers! As guardian of the number line, you must identify and eliminate composite numbers while protecting the irreducible primes that form arithmetic's building blocks.

The game board displays cascading integers from above. Analyze each number's divisibility—multiples of 2, 3, 5, and 7 form the initial threats, but later waves introduce semiprimes and higher composites requiring factorization. Click composites to shatter them; accidentally destroying a prime damages your "Mathematical Integrity" meter. Special "Prime Shield" power-ups temporarily highlight composites, while "Factorization Bombs" clear entire rows sharing common factors.

Progress through number theory lessons disguised as levels: the Sieve of Eratosthenes, twin prime conjectures, Goldbach partitions. "Mathematician Mode" removes all assists, challenging pure mental calculation. Leaderboards track highest primes preserved and fastest composite identification. With its elegant number visualization, genuine educational value approved by mathematics educators, and compelling risk-reward mechanics, this makes abstract algebra viscerally exciting. How long can you maintain the purity of the primes?

How to play free Keep Prime Numbers game online

Numbers descend from the top of the screen. Quickly identify composites (numbers with divisors other than 1 and themselves) and click to eliminate them. Let primes fall safely to the bottom collection zone. Memorize divisibility rules: even numbers (except 2), numbers ending in 5, digit sums divisible by 3. Chain composite eliminations for score multipliers!