Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
7 4 Bug's Eye
You are a bug sitting in one corner of a cubic room. You wish to walk (not fly) to the extreme opposite corner – the corner furthest from you. Describe the shortest path that you can walk.
geometry trigonometry Submitted by Ravi
7 6 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 ...
5 13 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 ...
7 7 Interview Question - Databases
This is a common interview question at companies like Google and Amazon: “Explain a database in three sentences to your eight-year-old nephew.” This question has an infinite number of solutions. Fee ...
5 8 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
7 3 Tea and Wine
You take a spoon of wine from a barrel of wine and put it into your cup of tea. Then you return a spoon of the (non-uniform) mixture of tea and wine from your cup and put it in the barrel. Now you ha ...
Math logic Submitted by Ravi
4 1 There are only 4 circles and none of them touch
Source: reddit.
optical illusion Submitted by Ravi
2 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 ...
6 8 Non-Adaptive 12 Identical Balls
Okay - so I posted this puzzle to reddit a few weeks ago and one guy had the following comment: Same problem, but your solution must be non-adaptive. IOW, specify the weighings that you will make up f ...
Math logic unsolved Submitted by Aakash
5 6 Balloon in an Elevator
A person is holding on to a helium balloon in an elevator. The elevator cable snaps, and at the exact same moment, the person lets go of the helium balloon. In the perspective of the person in the el ...
physics relativity Submitted by Aakash
5 5 Betsy and Patsy
“We were born on the same day of the same year,” said Betsy. “And we have the same mother and father,” said Patsy. “But we’re not twins!” the two exclaimed. Can you explain?
8 All Apples
On the market, mrs. Jones and mrs. Smith sell apples. Mrs. Jones sells her apples per two for 0.50 euro. The apples of Mrs. Smith are a bit smaller; she sells hers per three for 0.50 euro. At a certa ...
mathematics ratios Submitted by Valentin
9 1 Three Idols
Here's a classic: Three gods A, B, and C are called, in some order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a comp ...
5 2 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
2 4 What is the sum of 1+2+3+4+5 . . . (forever)?
What is the sum of 1 + 2 + 3 + 4 . . . all the way to infinity?
infinity Submitted by Tarun245