KAKURAKU
Intuition vs Math — Who Wins?
Free · Designed for iPad. Not verified for macOS.
Monty Hall, Birthday, Bayes, Three Prisoners, Newcomb — experience 12 probability paradoxes through intuition quizzes and live simulation. Your intuition will be tested.
KAKURAKU is an interactive educational app for experiencing probability paradoxes through hands-on simulation.
The 10th installment in the SUUGAKU / BUTURAKU / DENRAKU / HARAKU / NETURAKU / KORAKU / RYURAKU series. The theme is "probability." Experience 12 famous probability paradoxes through four interactive phases.
[4 Phases for Deep Understanding]
1. Intuition Quiz
Answer with your gut feeling first. Most people get it wrong.
2. Simulation
Run hundreds of trials and see the results with your own eyes.
3. Explanation
Why does intuition fail? Mathematical explanations bring that "aha" moment.
4. Comprehension Check
Test your true understanding with applied questions.
[12 Probability Paradoxes]
1. The Door Trap — Monty Hall Problem (switching wins 2/3 of the time?)
2. Miracle Classroom — Birthday Paradox (50%+ chance with just 23 people?)
3. The Gold Box — Bertrand's Box (your 1/2 intuition is wrong?)
4. Reversal Statistics — Simpson's Paradox (parts and whole tell opposite stories?)
5. Envelope Dilemma — Two Envelope Problem (should you always switch?)
6. Test Trap — False Positive Problem (positive result yet only 16% infected?)
7. Sleeping Princess — Sleeping Beauty Problem (1/2 or 1/3? Still unsolved)
8. Endless Bus — Bus Waiting Paradox (average 5 min but you wait 10?)
9. Red Streak — Gambler's Fallacy (black is "due" next?)
10. Infinite Gamble — St. Petersburg Paradox (infinite expected value?)
11. Warden's Verdict — Three Prisoners Problem (does A's fate change?)
12. The Predictor's Boxes — Newcomb's Paradox (one-box or two-box?)
[Features]
- Interactive simulations — see it to believe it
- Run single trials, 100x batches, or 1000x batches to watch probabilities converge
- Live formulas and numerical values
- Dark mode / Light mode
- Japanese / English support
- Works offline (network is used only for ad delivery)
[Monetization & Ads]
- This app is free to download and use
- No in-app purchases, no subscriptions, no paid unlocks
- A banner ad (Google AdMob) is shown at the bottom of the screen
- An interstitial ad may be shown when you clear a stage
- On iOS, personalized ads are only delivered after the user grants App Tracking Transparency (ATT) permission
[Recommended For]
- Students studying probability and statistics
- Anyone curious about the gap between intuition and mathematics
- Teachers looking for interactive teaching materials
- Anyone who wants to truly internalize "why is it that way?"
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
- Improved stage-clear navigation: the back button is hidden on the final screen so the clear flow always plays
- Newcomb's Paradox: the simulation now resets when you change the predictor's accuracy
- Minor bug fixes and stability improvements
The developer, Fuji Bit Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Identifiers
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Fuji Bit Inc.
- Size
- 24.8 MB
- Category
- Education
- Compatibility
Requires iOS 13.0 or later.
- iPhone
Requires iOS 13.0 or later. - iPad
Requires iPadOS 13.0 or later. - iPod touch
Requires iOS 13.0 or later. - Mac
Requires macOS 11.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- Japanese
- Age Rating
4+
- 4+
- Contains
Advertising
- Copyright
- © 2026 Fuji Bit