These are some of my favorites logic puzzles, math puzzles, brain teasers, andPlease if you have anyIf I like them, I'll add them to this page. people to thank for giving me these riddles all of whom I cannot remember. sure my father is one of them, and is another. In no particular order, other than alphabetical. - A Collection of Quant Riddles With (some) Answers - Haidong Wang's Difficult Puzzles and Brain Teasers - Iftach Nachman's Riddle page - Nick's Mathematical Miscellany, most notably Nick's Mathematical Puzzles - Paul Hsieh's puzzles - Rustan Leino's puzzle page - Syvum Brain Teasers and Math Puzzles - Tanya Khovanova's favorite puzzles - The Math Circle: Problems of the Week - Seven Puzzles You Think You Must Not Have Heard Correctly (with solutions) Find a 5 digit number, as big as possible, that when you multiply it by a single digit number, you get a six digit number, in which all digits are Create the number 24 using (all of) 1, 3, 4, and 6.

You may add, subtract,You can (and must) use eachNote that you may not "glue" digits together. * 3 is not a solution. 13 * 4 * 6 is not a solution either (powers There are 100 prisoners locked up in solitary cells. There is a central living room with one light bulb; the light bulb is initially off. can see the light bulb from his cell. Every day, the warden picks a prisoner at random (i.e., the warden may pick one prisoner multiple days in a row), and that prisoner is taken to the living room. In the room, the prisoner can do one of three things: 1) toggle the light switch, 2) do nothing, or, 3) assert that all 100 prisoners have been in the living room at least once. assertion is false, all 100 prisoners are shot. If it is true, they go free. Before they were locked up, they got an hour to discuss a plan. [I know of at least three solutions, only one of which will get them out within their lifetime. Try to estimate the runtime of your

A person cashes a cheque in the bank, and after he leaves the bank he buys chewing gum for 50 cents. Now, he didn't have any money when he entered the bank and when he counts the money in his pocket now he sees, to his utmost surprise, that the bank teller made a mistake: instead of the dollars he gave him the same number of cents, and instead of cents, he gave him the sameThe most bizarre situation was, that after buying the chewing gum, he now has twice the amount of money on the original cheque. was the amount on the cheque? [Try not to write a program to solve this. There is an analytical solution.] You and an opponent are playing a game where each person, in turn, gets to place one coin on the surface of a round table. The only rules are that the coins have to be placed flat on the table, and you are not allowed to place a coin on top of another one. The last person to successfully place a coin onIf you get to play first, what is your winning strategy?

You have 11 coins, one of which is slightly heavier or lighter. a balance, can you find the coin within 3 tries and say whether it's lighterOlde English Bulldog Puppies For Sale In MdNow do the same with 12.Sphynx Cat For Sale New Mexico You have 100 bags with coins. Prom Dress Rentals In Charlotte NcAll coins are equal, but one bag contains coins that are all 1 gram heavier than the coins in all the other bags. a scale (not a balance) that you can use only once, can you find the bag with You have two wicks and a box of matches. Both wicks burn for 60 minutes each, but they burn irregularly, i.e., any partial amount of wick that burned says nothing about the amount of time that passed.

How do you measure 45 minutes? A Classic: you come to a fork in the road. One road leads to Hell, the otherOn both sides of the road there is a person. One is a pathological liar (everything he says is false), the other a pathalogical truth teller (everything he says is true). If you get to ask a single question to one of them, what would you ask to choose which road you will continue your journey You have a number that consists of 6 different digits. by 2, 3, 4, 5, and 6 yields, in all cases, a new 6-digit number, which, in all cases, is a permutation of the original 6 different digits. I go to a party with my wife. When we get there, four other couples arrive atWe all know each other, so we all greet each other. can be a handshake, a kiss, a hug, or whatever. When everyone is done I ask everyone how many times they shook another person's hand. All answers I getGiven that nobody greets their own spouse, how many hands did Every day, the prison warden takes out his 100 prisoners to play an evil game.

He places them in a circle where everyone can see each other. a hat on each prisoner's head. The hat is either red or white and he always gives the same hat to the same person. The prisoner cannot see the color ofThen, on his command, all prisoners with a white hat have toIf one too few or one too many steps forward, they will all beIf they do it right, they all go free. If they all do nothing, they all go back to their cells and the game continues the next day. prisoners know there is at least one person with a white hat, how many days did it take for the prisoners to get out, and how did they do it? are not allowed to communicate in any way about the color of their hats. fear of execution, they don't.) You have 55 matches arranged in some number of piles of different sizes. now do the following operation: pick one match from each pile, and form a newYou repeat this ad infinitum. What is the steady state? [Once you solve this puzzle, you can play around with this little Ruby program to visualize the process.]

Another Classic: there are three desk lamps standing on a desk in room A. however, are in room B where you cannot see the lamps. There are three light switches in room B that control the three desk lamps in room A. switches are in the off position. You get fifteen minutes to think and act and then you will be brought to room A, where you have to state which switch corresponds to which lamp. What do you do? You throw three darts onto the surface of a globe, each from a randomly chosenWhat is the probability that all three darts are in one How do you fill a 100-liter aquarium with 50 liters? All you get is the aquarium and a water hose. A monk walks up a mountain to a church; it takes him a day. The next day he walks down the mountain. That also takes him a day. a time of day where the monk is in the exact same spot at the exact same time as the other day. What's the next number in the following sequence? A riddle for computer scientists: if you have an array of positive numbers,