Support
Contact and FAQ for the KAKURAKU app
Frequently Asked Questions
Q. Which devices are supported?
iPhone / iPad with iOS 15.0 or later, and Android phones and tablets with Android 7.0 (API level 24) or later.
Q. Is the app paid?
No. The app is free, with no in-app purchases, subscriptions, or paid content unlocks.
Q. Does it work offline?
All features except ads work offline.
Q. Which languages are supported?
73 languages, including English and Japanese. The app follows your device language automatically.
Q. What about ads?
A Pangle banner ad is shown at the bottom of the screen, and a full-screen (interstitial) ad may be shown when you clear a stage and return home (including when you leave a stage during the comprehension check). There is no paid option to remove ads. You can turn off personalized ads in "About this app" > "Ad settings" (on iOS, this appears after you have answered the tracking dialog). See the Privacy Policy for details.
Q. Can I quit during the comprehension check?
Yes. If you tap the back button at the top left during the comprehension check (or press the back key on Android), the app asks "Leave this stage?". Choose "Leave stage" to return to stage select (as when you clear a stage, a full-screen ad may be shown). During the intuition quiz, simulation and explanation, the back button takes you straight back to stage select.
Q. Is my progress saved?
No. Every stage can be played from the start at any time from the home screen. The only things the app stores on your device are your theme setting and your personalized-ads choice.
Q. Can I use it in class?
Yes. Feel free to use it in schools, tutoring, or self-study.
Q. The simulation doesn't match the theoretical value exactly.
Each simulation runs random trials, so the results scatter around the theoretical value. The more trials you run, the closer they get (the law of large numbers) — which is one of the things KAKURAKU wants you to feel for yourself.
Reporting Bugs
To help us resolve issues quickly, please include:
- Device name (e.g. iPhone 16 / Pixel 10a)
- OS version (e.g. iOS 18.2 / Android 16)
- App version (e.g. 3.0.0)
- The stage where it happened, a description and reproduction steps
About the App
KAKURAKU is an educational entertainment app for experiencing 14 famous probability paradoxes — including the Monty Hall problem, the birthday paradox, Bayesian false positives and Benford's law — in four phases: an intuition quiz, a simulation, the explanation, and a comprehension check.
Version: 3.0.0