Screwy Pirates brain teaser - interactive puzzle

Five rational pirates vote on how to split 100 gold coins, and you work out the split by backward induction from a one-pirate crew up.

The story animates the rules. Five pirates, ranked senior to junior, loot a chest of 100 gold coins. The most senior pirate proposes a split. All five vote, and at least 50% must vote yes - with five pirates, that means three votes, and the proposer votes too. If the proposal clears the bar, it stands and no one is harmed. If it fails, the senior pirate is fed to the sharks and the process repeats with the next most senior pirate proposing, with the 50% bar recalculated for the smaller crew each round.

Three assumptions close the story: all pirates are perfectly rational; they want to stay alive first and maximise gold second; and, being bloodthirsty, they prefer fewer pirates on the boat when outcomes are otherwise equal. Then the question: how will the gold be divided?

From there you move to the answer builder at /brain-teasers/screwy-pirates/answer. You pick a crew size from 1 to 6, fill in how many coins each pirate keeps, write out your reasoning in a text box, and write an equation for the pattern you found. A full narrated breakdown lives at /brain-teasers/screwy-pirates/breakdown.

Why quant interviews test this

This is a canonical quant interview question about backward induction with voting. The interviewer wants the base case stated, the recursion run cleanly, and the buy-the-cheapest-votes logic named - and the standard follow-ups (more pirates, a supermajority rule, different tie-breaks) all test whether you built the machine or memorised 98, 0, 1, 0, 1.

The Screwy Pirates guide covers how scoring works, the strategy that wins, a worked example and the mistakes most players make.

More Brain Teasers games

• Tiger and Sheep - A hundred rational tigers and one sheep on a magic island, where any tiger that eats becomes a sheep itself - solved by induction on parity.
• The Split Deal - The prisoner's dilemma played as a story: two thieves, separate rooms, and one offer each.
• Stag or Hare - The stag hunt as a story: two equilibria, and a choice that comes down to trust.
• One Offer, No Discussion - The ultimatum game as a story: one split of 100 pounds, one accept-or-reject, no negotiation.
• The Growing Pot - The centipede game as a story: a pot that doubles on every pass, and logic that says take it immediately.
• Two-Thirds of the Room - The Keynesian beauty contest as a story: pick the number closest to two-thirds of the room's average.
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• Play Screwy Pirates
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• The step-by-step breakdown
• The Screwy Pirates guide
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