Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
4 2 Boys and Girls
To help solve an acute national over-population problem, a government issues a radical decree that families must stop having children as soon as they have had one son. After a while, there are some ...
Doable
5.4
4 2 Troll Toll
You are on your way to visit your Grandma, who lives at the end of the valley. It’s her birthday, and you want to give her the cakes you’ve made. Between your house and her house, you have to cross ...
Submitted by Aakash
Easy
3.1
3 3 Guilty Innocence
I am a drug dealer. I have been questioned by the police with all of my drugs surrounding me, but I was not arrested. Why?
Easy
2.6
3 3 Products Algorithm
Given an array A[1...N] of integers, create an array O[1...N] where O[i] = the product of all elements in A except for the ith element. For example, if N = 3, and A = {6, 4, 2}, O = {8, 12, 24} The t ...
Doable
4.0
3 3 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
3.3
3 5 Don't Mate in One
This problem was first publicized by Karl Fabel, a German chess problemist. Find a move for white that will not result in an immediate checkmate of the black king.
logic chess Submitted by Aakash
Hard
7.0
2 2 Up and Down
Explain the following scenario: A man lives on the twelfth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets int ...
Submitted by Valentin
Hard
7.5
4 2 Don't Eat Me!
Would you rather a crocodile attack you or an alligator?
Submitted by Aakash
Doable
4.7
5 1 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
3 Gone Camping
Camp Crona’s cook, Allison, was just about to begin preparing the picnic lunch for all the campers. She already knew she needed to fill 55 bowls of the same size and capacity with the same amount of fo ...
mathematics Submitted by Aakash
Easy
3.0
5 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
5.0
1 6 Good luck at an interview with Google
I just came across these Google interview questions… impossible: How many golf balls can fit in a school bus? How much should you charge to wash all the windows in Seattle? How many piano tuners are ...
google open-ended Submitted by Valentin
Hard
7.0
3 2 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
6.0
5 1 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
7.6
8 Simple 24
Why is that if p is a prime number bigger than 3, then p^2-1 is always divisible by 24 with no remainder?
Submitted by Aakash
Hard
7.3