Brain Teasers and Puzzles

Brain teasers, puzzles, riddles, and other challenges

Difficulty - Medium, Rebus

Rebus Puzzle 14

What common word or phrase is this rebus referring to?

 serGeant
  geNeral
 ensIgn
 priVate
 colOnel
  adMiral

Solution

Moving up the ranks

(Each line is a rank in the military, and “moving” is spelled upwards among the ranks.)

Difficulty - Easy, Logic Puzzles

Four-Card Problem

You see four cards with A, D, 3, and 6 face-up. You know that each card has a letter on one side and a number on the other side.

You are told that cards with a vowel on one side must have an even number on the other side. Which cards do you need to turn over to test if this rule is broken?

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Difficulty - Medium, Interview Brain Teasers, Logic Puzzles

You have six guesses to figure out a 3 digit code. After each guess, you will be told exactly how many digits are correct but in the wrong place and how many digits are correct and in the right place. You have made these five guesses already:

865: exactly one digit in the right place
964: exactly one correct digit but in the wrong place
983: no correct digits
548: exactly two correct digits but in the wrong places
812: exactly one correct digit but in the wrong place

What is the correct 3 digit code?

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Difficulty - Medium, Interview Brain Teasers, Probability

Tennis in 2 or 3 sets

In a best of 3 tennis match, the player that first wins 2 sets wins the match. For a 3-set tennis match, would you bet on it finishing in 2 or 3 sets?

This question was asked in an actual D. E. Shaw quant trading interview.

Preparing for a brain teaser interview? Check out our ultimate guide to brain teaser interviews.

Difficulty - Medium, Interview Brain Teasers, Logic Puzzles, Simple Math

Guess the Number

Jake has a 4-digit number in mind and asks Raj to guess the number. Raj can have 7 guesses, and Jake will give him some hints after 6 guesses.

Raj makes these 6 guesses:

6 3 5 8
9 3 0 6
4 8 8 2
6 7 2 8
1 1 9 1
5 6 2 7

These were all wrong, but Jake says every guess had exactly one (and only one) correct digit in the correct position. Additionally, all the digits are different.

What should Raj’s 7th guess be?

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Difficulty - Hard, Rebus

Got Hero Hero Puzzle

What common word or phrase is this rebus referring to?

GOT GOT GOT GOT HERO HERO HERO HERO HERO HERO HERO HERO HERO HERO

Click to show solution

Forgotten heroes (“four got ten heroes”)

Difficulty - Hard, Geometry, Matchstick Puzzles

Four Squares Match Puzzle

Move exactly 2 matches to make these five squares into four squares of equal size, without any matches left over.

Chess, Difficulty - Medium

Chess Knight Assassin

From its starting position, the white knight that captured the black queen has moved exactly eight times to get where it is now. How is this possible?