The Paradox You Can Play

Everyone thinks it's 50/50. The math says otherwise. Pick a door — or a card — switch or stay, and watch a counterintuitive truth assemble itself from your own results, one game at a time.

📡 Telecommunication Engineer Project · by Chokri Mohamed

🚪 The Three Doors

One door hides a Ferrari. Two hide goats. Pick a door, the host opens a goat door — then decide: stay or switch?

Pick a door — any door.
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Games Played
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Win Rate When Switching
theory 66.7%
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Win Rate When Staying
theory 33.3%
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Your Lifetime Games
Auto-simulate:
Why switching wins 2/3 of the time: your first pick is right only 1/3 of the time — and opening a goat door never changes that. The 2/3 probability that the car is behind one of the other doors collapses onto the single remaining closed door. The host isn't revealing random information; he knows where the car is and deliberately avoids it. Switch, and you inherit his knowledge.

🃏 The 52-Card Deck

Same paradox, brutal numbers. Pick one card face-down — 1/52 chance it's the Ace of Spades. Then watch 50 cards get flipped, one by one, every one not the Ace. Keep your card, or swap for the last face-down one?

Pick one card from the deck.
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Games Played
0%
Win Rate When Swapping
theory 98.1%
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Win Rate When Keeping
theory 1.9%
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Your Lifetime Games
Why the last card holds 51/52: your pick is locked at 1/52 the instant you touch it. The other 51 cards collectively own 51/52 — flipping 50 known non-Aces removes nothing from that share, because the flipper knew where the Ace was. The entire 51/52 collapses onto the single surviving face-down card. Swapping turns a 1.9% chance into a 98% chance. The bigger the deck, the more absurd "it's 50/50" sounds.

🌐 Global Stats — Every Player, Forever

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When chodev.online goes live, every game played by every visitor around the world will be recorded here — an ever-growing, permanent dataset proving the paradox in real time. Each game is tracked separately, because they don't share the same theoretical odds.

🚪 Three Doors

theory: switch 66.7% · stay 33.3%
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Lifetime Games
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Switch Win Rate
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Stay Win Rate

🃏 52 Cards

theory: swap 98.1% · keep 1.9%
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Lifetime Games
0%
Swap Win Rate
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Keep Win Rate

Every result is saved to the server permanently — this panel shows the worldwide totals in real time. (The reset button clears only your own browser.)