EveryMemoryPrime or Not
A 60-second sprint: a number flashes, you tap Prime or Not prime. Beat your own best. Free, in your browser, no sign-up.
⚡ Quick answer
Prime or Not is a timed game where you judge whether each number is prime as fast as you can for one minute. The score is for fun and self-tracking, compared only to your own past, and it is not a medical or cognitive test.
Key takeaways
- Free in your browser, no sign-up - a 60-second prime or not sprint.
- Correct calls add a point, wrong calls subtract one.
- Numbers run from 2 to 99 with a built-in prime check.
- A fun self-relative number game, not a medical or cognitive test.
Prime or Not is a 60-second number sprint. A number from 2 to 99 appears and you tap Prime or Not prime. A correct call scores a point, a wrong one costs you a point. Keep the pace up and beat your own best. Play it above.
It is free, needs no sign-up, and your best score is saved only on your device. There is no account and nothing to install.
How to play
One minute of snap decisions:
- Tap Start to begin the 60-second timer
- Read the number and tap Prime or Not prime
- A correct call is plus one, a wrong call is minus one
- At zero seconds your final score and best are shown
No account is needed and your best score stays on your device.
What it trains
Snap prime judgments lean on:
- Number sense and divisibility shortcuts
- Processing speed under a timer
- Focus and quick decision making
In honesty you mostly get faster at spotting primes. It is fun practice, not an IQ measure or a clinical test.
Quick prime shortcuts
You rarely need to test every divisor:
- Even numbers above 2 are never prime
- Numbers ending in 5 (above 5) are never prime
- If the digits sum to a multiple of 3, it divides by 3
The honest way to read your score
Your best is a personal baseline. Fatigue and distractions shift it, so the only fair comparison is you versus your own earlier runs rather than anyone else.
Enjoy quick decisions? Try the reaction time test, or sharpen focus with tips on improving concentration.
⚠ When to talk to a professional
Prime or Not is a casual number game for fun and personal tracking, not a medical or cognitive assessment; for any real concerns about thinking or focus, consult a qualified professional.
