# MrCollatz — Find a counter example

> Find a counter example (iPhone/iPad app by CHRISTOPHER REBERGER.)

- Source: https://appshunter.io/ios/app/mrcollatz/id6824321965 (this page in markdown: same URL + `.md`)
- Developer: [CHRISTOPHER REBERGER](https://appshunter.io/developer/6824321967)
- Category: Education, Reference
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 2 MB
- Languages: American English
- Released: 2026-10-31
- Data updated: 2026-11-01

## What is MrCollatz?

Take any whole number. If it's even, halve it. If it's odd, triple it and add one. Repeat. The Collatz conjecture says you will always reach 1 — and no one has ever proved it.
MrCollatz lets you watch it happen with numbers far too big to do by hand.
• Start from a random number of 30 to 200 digits, or type in your own
• Run it all the way, or step through one move at a time
• Watch the trajectory charted live on a log scale, with the peak marked
• Six graph styles: area, line, bars, points, stepped and spiral
• See the step count, peak size, and how many 3n + 1 and n ÷ 2 moves it took
• Auto mode tests number after number and keeps a running total
Random starting numbers always leave remainder 3 when divided by 4, which tends to give the longest climbs before the fall.
And if a number ever refuses to come down, MrCollatz will tell you. You may have disproved a famous conjecture — show it to a maths person.
No ads, no accounts, no tracking. Everything runs on your device.

## Is MrCollatz safe?

Not enough ratings yet to assess MrCollatz.

## Is MrCollatz legit?

MrCollatz appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for MrCollatz is 65 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 1 release)

### 1.0 — 2026-10-31

No release notes.

## More apps by CHRISTOPHER REBERGER

- [Memento Muscae](https://appshunter.io/ios/app/memento-muscae/id6825129852)
- [SlowLetGo](https://appshunter.io/ios/app/slowletgo/id6826173677)

All apps by CHRISTOPHER REBERGER: https://appshunter.io/developer/6824321967

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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 2026-11-01.*