So here's the brainteaser I was asked to solve at a recent interview (at a company that shall remain nameless):

Five pirates discover a treasure of 100 gold coins. They decide to divide up the treasure as follows: the youngest pirate will suggest a scheme for dividing the coins, and all five pirates will vote on the proposal. If the youngest pirate gets the approval of the majority, his plan for dividing the coins will be adopted. If his plan is rejected, then the youngest pirate will be killed, and the next-to-youngest pirate will suggest his own scheme, with the same conditions (and possible punishment) as before. And so on down the line. (Note that if a tie vote results, the proposal is considered to have failed.)

The question is, assuming that all the pirates are rational, and that their preferences are 1) to stay alive, 2) to get as much treasure as possible, and 3) to kill other pirates, how will they end up dividing the treasure?

(I got the right answer, but only after several wrong turns and quite a bit of prompting from my interviewer. Got the job, too.)