Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
4 3 Time To Fuse
You have a string-like fuse that burns in exactly one minute. The fuse is inhomogeneous, and it may burn slowly at first, then quickly, then slowly, and so on. You have a match, and no watch. How do ...
physics logic rates Submitted by Valentin
Doable
4.5
4 8 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
6.7
3 1 No if() no abs()!
This is inspired by the puzzle "No if() only abs()" : Given two variable a and b, construct a function f(a,b) which return the maximum one in {a,b}. You can only use +- · / (basic arithmetic operator ...
Hard
10.0
3 4 Tooth Paste, : Profit
There are 2 Persons, Who Saves Money. One person Bought a tooth Paste of 100 gms, for Rs. 40. The second person Buys, Two 50 gms for Rs. 20 each. at same shop, the same company of Pastes. No Extra past ...
Doable
6.0
9 Unfair Coin
Say you have an unfair coin: a coin whose probability of flipping heads and flipping tails is unknown but nonzero. Can you design a game where you and your opponent have an equal chance of winning?
Doable
5.0
2 11 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
4 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
2.8
5 8 Psycho Killer
While at the funeral of her mother, she met a man whom she did not know. She thought he was amazing, her dream guy, and she fell in love with him but never asked for his number and could not find him ...
Submitted by Valentin
Easy
3.0
6 6 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
5 4 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
4 1 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
3.1
4 1 Clock Hands - Google Interview Question
How many degrees are there in the angle between the hour and minute hands of a clock when the time is a quarter past three?
logic mathematics Submitted by Valentin
Doable
3.5
4 4 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
5.0
5 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
2.9
5 3 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