Primes

Prime or Composite: a number from 2 to 999. Work it out by hand, then call it. Every answer shows the method.

Privacy policy

Primes collects no data. Nothing you do in the app leaves your phone.

• No accounts, no sign-in, no ads, no analytics, no tracking.
• The app makes no network requests.
• The primes you've found and your chosen look are saved on your iPhone only (in the app's local settings). They're included in your device's own backups, like any app's settings, and deleting the app deletes them.
• Nothing is shared with or sold to anyone, because nothing is collected.

If this ever changes, this page will change first. Last updated November 2, 2026.

Support

Found a bug, or a number whose explanation looks wrong? Open an issue on GitHub and say which number and which tier.

Made by Chad Stewart.