But Never Moves
What can go through towns and cities, over hills and mountains, but never moves?
Zero-less Factors
What two numbers contain no zeroes and can be multiplied together to produce 100000?
How Many Friday the 13th in a Year
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.
Ferry Boat Problem
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…
Converge to an Integer
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…
Sum of Powers
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.
Finish My Wordle
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…
Russian Roulette Riddle
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…
Mate in 4 Chess Puzzle 1
White to play and mate in 4.
Vocabulary Puzzle
Quick vocabulary puzzle – given the middle four letters of each word, figure out these 8-letter words:
Consecutive Numbers Grid Puzzle
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…
The Impossible Puzzle
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…
Four Lines of Four Coins
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…
Matchstick Math 3
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!
Truel
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…
Mate in 3 Chess Puzzle 1
White to play and mate in 3.
Rebus Puzzle 17 – NAFISH
What common word or phrase is this rebus referring to? NAFISHNAFISH
Reroll the Die
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…
7 Quant Interview Questions and Answers
Quant interview question often contain brain teasers involving mathematics, statistics, and logic. The goal of these questions is to assess your quantitative and reasoning abilities, which can be highly relevant to working as a quant analyst, trader, or developer. Here…
I Like the Numbers 4 and 5
I like the numbers 4 and 5. I like to add 4’s and 5’s together to make other numbers, such as 4 + 4 + 5 + 5 + 5 = 23. How many numbers from 1 to 1000 can…
Lions and Sheep
On a magical island, there are 100 lions and 1 sheep, all of which can live by eating the plentiful grass on the island. Any lion that eats the sheep will magically turn into a sheep afterward, such that there…
7 Actual Brain Teaser Interview Questions and Answers
Brain teaser interview questions were quite common in tech, finance, and consulting interviews for a period of time. Here are 7 brain teaser interview questions and answers encountered in actual interviews, including engineering interviews at Apple and Microsoft – how…
Leave Two Squares
Remove 6 matches from the diagram above to leave two squares, with no extra matches lying around.
Mate in 6 Chess Puzzle 1
White to play and mate in 6. This one is very tough!
Password to Exclusive Club
A man wants to enter an exclusive club, but doesn’t know the password. He observes a few other patrons: Thinking he has figured it out, the man walks up and the doorman says “10”. The man replies “5” but it’s…