A prison warden was feeling capricious and played a game with the prison keys: Each prisoner is handed a key to another prisoner’s cell. Each prisoner will know which other prisoner was initially given the key to their cell (but…
The digital sum of a number is just the sum of the individual digits. E.g., the digital sum of 123 is 1 + 2 + 3 = 6. What is the digital sum of z = x + y?
If you have me, you want to share me. If you share me, you haven’t got me. What am I?
In this sharing game theory puzzle, 3 friends take turns taking from a jar of 1000 candies to share. For example, the 1st friend could take 500 candies, then the 2nd friend could take 400, and the 3rd friend would…
I am a 5-letter word. I am normally below you. If you remove my 1st letter, I am normally above you. If you remove my 1st and 2nd letters, I am all around you.
What common word or phrase is this rebus referring to? || READ ||
A rock paper scissors puzzle: Anya played 10 games of rock paper scissors against Blake Each time there was a winner (no ties) Anya used rock 2 times, paper 2 times, and scissors 6 times, but you don’t know the…
What can go through towns and cities, over hills and mountains, but never moves?
What two numbers contain no zeroes and can be multiplied together to produce 100000?
Some consider Friday the 13th (any Friday that falls on the 13th day of a month) unlucky. In a calendar year, how many Friday the 13th can occur? Find both the minimum and maximum.
Two ferry boats serve the same route on a river, but travel at different speeds. They depart from opposite ends of the river at the same time, meeting at a point 720 yards from the nearest shore. When each boat…
Given the iterative formula: xn+1 = sqrt(xn) + a There are some values of a for which a positive starting value for x results in this formula converging to an integer. For example, if a = 2, you would observe…
Find a combination of three different positive integers x, y, and z such that: x3 + y3 = z4 Hint: there’s a better way than brute force / trial & error.
These Wordle puzzles are nearly complete, you just need to finish them by figuring out the correct word. In each of these 5 puzzles, there should be just one or two valid answers remaining – find them! Haven’t played Wordle…
In the morbid game of Russian Roulette, a partially loaded revolver with a six-chamber cylinder is randomly spun, pointed at one of the players, and fired. If the revolver landed on an empty chamber, the lucky player is safe, and…
White to play and mate in 4.
Quick vocabulary puzzle – given the middle four letters of each word, figure out these 8-letter words: _ _ TABA _ _ _ _ CUME _ _ _ _ NERO _ _ _ _ IDEN _ _ _ _ NETA…
13 10 4 16 7 The cells in this 4×4 grid puzzle contain the numbers 1-16 each once. There are two rules to the arrangement of the numbers: Any two consecutive numbers must share a row/column (1 and 16 should…
This puzzle was coined the “Impossible Puzzle” by Martin Gardner, a famous math and science writer that liked to create and write about math games and puzzles. The puzzle is named as such because it appears to provide insufficient information…
Form four lines of four coins by moving exactly 3 of the coins below: Rules: Coins cannot be stacked on top of one another. A line of five or more coins is still only considered one line. The centers of…
Rearrange exactly 2 matches to make this a valid equation. In matchstick math puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That would make it too easy!
A truel is a three-way duel. The three participants take turns firing one shot at whichever opponent they choose, until only one is remaining. Allison, Ben, and Chase are in a truel, and have varying degrees of accuracy: Allison has…
White to play and mate in 3.
What common word or phrase is this rebus referring to? NAFISHNAFISH
Suppose there is a game in which you roll a fair, 6-sided die and win dollars equal to the outcome of the roll. How much would you expect to win on average? Suppose, if you don’t like the outcome of…