Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
7 7 The Neighbourhood
People say Einstein suggested that 98% of the world’s population couldn’t figure out the answer to this puzzle. It is not for the faint of heart: There are 5 houses each with a different color. Th ...
Hard
7.5
6 10 Find the Missing Number
In this table, each row across follows the same pattern of numbers. See if you can discern the pattern and fill in the missing number in the bottom row. 7 4 8 3 9 7 6 5 10 ? ...
patterns Submitted by Ravi
Doable
6.0
6 3 Clever Commuter
Every day, Fred takes the train to travel from his work back to Alkmaar, his place of residence. Usually, he arrives at the station of Alkmaar at six o’clock, and exactly at that moment he is picked ...
Submitted by Valentin
Hard
7.5
6 2 Salary
Three coworkers would like to know their average salary. how can they do it, without disclosing their own salaries.
Submitted by Aakash
Doable
6.0
6 6 The Female Star
My first two letters are a man. The first three a woman. The first four are a brave man. And in whole I am a brave woman.
riddle word puzzle Submitted by Valentin
Doable
4.3
6 8 Partitioning a set
In how many ways can a set of r objects be partitioned into subsets of k objects such that: all subsets are mutually exclusive each of k-object subset appears in exactly one of the partitions [Partit ...
Hard
8.7
6 5 Grey Squares Illusion
Square A is the exact same shade of gray as square B. It's true, check out the reconstruction.
Doable
6.0
6 10 Happy Handshaking
Jack and his wife went to a party where four other married couples were present. Every person shook hands with everyone he or she was not acquainted with. When the handshaking was over, Jack asked ev ...
Submitted by Valentin
Hard
8.0
6 7 Death by drawing?
You are a prisoner in a strange foreign land, and a random drawing will decide your fate. You are given 2 bags, 10 white marbles, and 10 black marbles. You are to place the marbles in the bags in any a ...
probability Submitted by Gene
Doable
4.4
6 10 Binary 5 digits
What is the base 10 equivalent of the highest 5 digit binary number?
Easy
2.0
6 1 What Number Is It?
So there are two students, that play a game with their teacher. They have 10 cards, each card is numbered 1,2,3,...,9,10. And then their teacher gives them two cards that is consecutive. For example, o ...
Easy
2.7
5 11 The Stealing Mailman
This is a fairly simple problem that can cause some people trouble. Kevin and Sophia want to mail high confidential letters between each other. They know that the mailman is crooked and opens the le ...
logic cryptography Submitted by Ravi
Doable
6.5
5 2 Age of Three Kids
One day, a guy from census come into a house. When he rings the bell, a lady comes out. He then asks how many people lives in her house, and their age. And then she says: I am 45 years old. I have thr ...
Doable
6.0
5 5 Matchsticks
This is a classic Martin Gardner puzzle. See the picture - the four matchsticks represent a martini glass and the match head represents an olive. Move just two matches so that the glass is reformed bu ...
logic spatial Submitted by Aakash
Doable
3.6
5 15 Crazy Google Interview Question
You are shrunk to the height of a nickel and your mass is proportionally reduced so as to maintain your original density. You are then thrown into an empty glass blender. The blades will start moving ...
Doable
6.0