5 Pirates Puzzle

Five pirates are figuring out how to divide up a newly plundered treasure of 100 gold coins. From most senior to least senior: Pirate A, Pirate B, Pirate C, Pirate D, and Pirate E. The rules: The most senior pirate…

Wrong Seat Probability

There is a fully-booked flight with 100 seats. The first person decides to ignore the seat assignments, and sits in a random seat. Each subsequent person sits in their assigned seats if available, or sits in a random unoccupied seat…

Card Pairing Game

You are playing a game with your friend using a standard deck of 52 playing cards. Each round, you flip over two cards: If both cards are black, you keep the cards and earn one point. If both cards are…

Base Rate Fallacy

What is the Base Rate Fallacy? In simple terms, it’s a common error we make in assessing likelihoods due to (a) over-emphasizing the rate of something within a group and (b) under-emphasizing how common that group is in the first…

Missing Dollar Riddle

The missing dollar riddle is a classic brain teaser that can trip up even savvy puzzle solvers: Three friends split the cost of a hotel room. They are charged $30, so each of them pays $10. Later the hotel manager…

Pigeonhole Principle

The Pigeonhole Principle is a simple and elegant concept: If you place more than n pigeons into n pigeonholes, at least one of the pigeonholes must contain more than one pigeon. More generally, if you need to make more than…

Slowing and Shrinking

Remove one letter from the word “SLOWING” to make another valid English word. Repeat this step until you are left with just one letter, ensuring every step results in an English word. What words did you make in the process?