# Primes: Prime or Composite — Spot primes by hand

> Spot primes by hand (iPhone/iPad app by Chad Stewart.)

- Source: https://appshunter.io/ios/app/primes-prime-or-composite/id6829131144 (this page in markdown: same URL + `.md`)
- Developer: [Chad Stewart](https://appshunter.io/developer/1895574914)
- Category: Education
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-11-02
- Data updated: 2026-11-06

## What is Primes?

A number from 2 to 999. Is it prime, or composite?

Primes is a small, quiet game for spotting prime numbers by hand. Work it out in your head, tap Prime or Composite, and see exactly how the answer is reached: the square-root bound, the divisibility trick that cracks it, the factors it splits into. A miss still teaches you something.

WHAT'S INSIDE
• Easy, Medium and Hard, so the numbers get sneakier as you do
• Every answer shows its method, step by step
• A star-shaped tool button that fans out Roots, Prime tricks and a Checklist, for when you're stuck
• Eleven divisibility tricks, from "last digit is even" to the chop tests for 7, 13 and 17
• 168 primes under 1,000. Each one lights up the first time you call it
• Three looks: Lamp (warm amber in the dark), Marginalia (gilt on a library green) and Phosphor (an 80s terminal), each in light and dark
• How to play, plus a short scrolling tour of why primes matter: the atoms of math, Euclid's proof that they never run out, the Ulam spiral, prime-year cicadas and the primes that keep your secrets

NO HOOKS
No accounts, no ads, no notifications, no tracking. It works offline, and nothing leaves your phone. Play a few, then put it down.

## Is Primes safe?

Not enough ratings yet to assess Primes.

## Is Primes legit?

Primes: Prime or Composite has limited verification signals. The AppsHunter Legitimacy Score for Primes is 58 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 2 releases)

### 1.0.1 — 2026-11-05

An improved How to play guide, plus updated privacy policy and support links.

### 1.0 — 2026-11-02

No release notes.

## More apps by Chad Stewart

- [Garden - Notes & Calm](https://appshunter.io/ios/app/garden-notes-and-calm/id6763959626)

All apps by Chad Stewart: https://appshunter.io/developer/1895574914

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-11-06.*