Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
2 3 The Easy Sum of 1..100?
Quick,without using a calculator, what is the sum of all numbers between 1 and 100 inclusive? Or 1..10 for that matter..
Submitted by Valentin
Easy
2.8
3 What number is next?
What number comes next in this sequence? 4, 20, 56, 120, 220, ?
Submitted by Aakash
Doable
4.3
2 1 Lockers
A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony: There are one thousand lockers and one thousand students in the school. The princip ...
Submitted by Aakash
Hard
7.1
3 1 Its waistline is a hexagon
Heart of Darkness, Coat of Grain, Was once alive, Now feels no pain, Never walks, but Leaves a Trail. Circle head and pointed tail. Grows shorter as the day goes on- Its waistline is a hexagon. Wha ...
Submitted by Valentin
Doable
5.2
1 2 Stuck in a brick building
A man is stuck inside an all brick building (floor, ceiling, and walls are all brick), that has no windows and no doors, and inside with him he has only a wooden board and a saw, how does he get out? ...
Submitted by Valentin
Doable
5.3
3 1 Power of 2 (Microsoft Interview)
Given any number n, using one line of C (using no external libraries or functions) code, determine if n is a power of 2. Return 1 if n is a power of 2 and 0 if not.
bitwise powers Submitted by Aakash
Doable
6.0
2 2 The Way Engineers Think
A priest, a doctor, and an engineer were waiting one morning for a particularly slow group of golfers. Engineer: What’s with these guys? We must have been waiting for 15 minutes! Doctor: I don’t ...
Submitted by Aakash
Doable
6.0
1 5 Right or Left?
This is interesting. Look at the animation below. Do you see the girl spinning clockwise or counter-clockwise
Doable
3.3
3 2 The Price Is Right
Many shops have prices set just under a round figure, e.g. $9.99 instead of $10.00 or $99.95 instead of $100.00 . It is assumed that this is done because the price seems lower to the consumer. But th ...
Submitted by Aakash
Hard
7.0
2 2 The North Pole Bear Puzzle Reloaded
A man walks 1 mile south, then 1 mile east, and finally 1 mile north to find himself in exactly the same position as he started. He is NOT at the north pole, nor does he shoot a bear. Where is he? ...
brain teaser geometry Submitted by Ravi
Doable
6.0
3 2 Open Water
A man is in a rowing boat floating on a lake, in the boat he has a brick. He throws the brick over the side of the boat so that it lands in the water. The brick sinks quickly. The question is, as a r ...
Submitted by Valentin
Doable
6.0
3 The fake coin
You have 9 coins which all look identical but 1 of them weight less than the others. You have a two pan balance (see the picture) with which you can measure twice, and with this 2 measurements you ha ...
Submitted by Aakash
Doable
4.0
2 Farmer's Market
You’re a farmer. You’re going to a market to buy some animals. On the market there are 3 types of animals for sale. You can buy: Horses for £10 each, goats for £1 each and ducks, you get 8 of these ...
Submitted by Aakash
Doable
4.7
1 The fisherman and the Hunter
The are two men that always tell the truth except for the days when they are lying. The fisherman lies on Monday, Tuesday and Wednesday. The Hunter lies on Thursday, Friday and Saturday. Today the ...
Submitted by Valentin
Easy
3.1
3 3 Brilliant People
There are three genii standing in a row in a room facing the same direction. Thus, the genius at one end can see the two genii ahead of him, the genius in the middle can only see the one genius ahea ...
Submitted by Ravi
Doable
5.2