Prime or Not

Time

Score

Streak

Best

A number flashes on screen. Tap Prime if it has no divisors other than 1 and itself, or Not Prime otherwise.
You have 30 seconds total per round. Each number also has its own quick timer — answer before it runs out, or it counts wrong.
Correct answer: +1 point and the next number flashes faster.
Wrong or too slow: −1 point (minimum 0) and your streak resets.
Numbers get bigger as your score climbs. By definition, 1 is not prime and 2 is prime.
Keyboard: ← / P for Prime, → / N for Not Prime, Space to start.

Decide fast: prime or not? 30 seconds, sharper each round.

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Ready?

A number will flash on screen — decide if it's prime before the bar runs out. 30 seconds per round.