Card Trick Without the Trick

This is a card trick without the trick. there is no sleight of hand, no tricks up my sleeve, no magic whatsoever. it’s all done with logic, yet it will amaze most people. Joel and i are working together as a team to do the trick. Babak will be the culprit.

Pirates Revisited

A slightly different version of the original pirates problem (read that one first to get all the rules). 6 pirates, only one gold coin. as before, the pirates are super-smart, and they value, in this order: (i) their lives, (ii) getting money, (iii) seeing other pirates die. so if given the choice between two outcomes,… Read More »

Fuse on Fire

A mad bomber is out on the job, making bombs. he has two fuses (pieces of string) of varying thickness which each burn for 30 seconds. unfortunately he wants this bomb to go off in 45 seconds. he can’t cut the one fuse in half because the fuses are different thicknesses and he can’t be… Read More »

Dave’s on Fire

dave winer is stuck on a deserted island, with lots of trees, which is very thin and ten miles long (east to west). large cliffs surround the entire island and if he jumped off, he wouldn’t survive the fall. a fire starts burning at the west side of the island. unfortunately this island always has… Read More »


problem: using 31 dominoes, where one domino covers exactly two squares, can you cover all the empty squares on this chessboard (which has 62 spaces). if so, how? if not, why?    Solution i think everyone’s first inclination is to try and figure out how it is possible. then again, if you’ve heard a bunch… Read More »

Easy River Crossing

Three cannibals and three anthropologists have to cross a river. the boat they have is only big enough for two people. if at any point in time there are more cannibals on one side of the river than anthropologists, the cannibals will eat them. what plan can the anthropologists use for crossing the river so… Read More »


Part I: draw a square. divide it into four identical squares. remove the bottom left hand square. now divide the resulting shape into four identical shapes. Part II: draw an equilateral triangle (all sides same length). divide it into four identical shapes. remove the bottom left hand shape. now divide the resulting shape into four… Read More »


Five webloggers – joshua Allen, meg Hourihan, jason Kottke, robert Scoble, and joel Spolsky – were competing for karma points on the major search engines: google, yahoo, altavista, lycos, and msn. karma was distributed on a five point scale. the most popular weblog received 5 points, and the least popular received 1 point. for each… Read More »

Hard River Crossing

a disfunctional family has to cross the river. on one side of the river are a mom and 2 daughters, dad and 2 sons, the maid and the dog. there is a boat only big enough to hold 2 people (counting the dog as 1 person). only the adults are capable of operating the boat.… Read More »

Classic Weighing

this is a classic problem which i have heard many times before. this is the “harder” of the two problems, since in this one, you do not know if the invalid item weighs more or less than the others. solving it is only half the battle. writing up a solution that anyone including your grandma… Read More »