Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
3 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
3 A Pharmacist's Nightmare
You have 5 jars of pills. Each pill weighs 10 gram, except for contaminated pills contained in one jar, where each pill weighs 9 gm. Given a scale, how could you tell which jar had the contaminated p ...
Submitted by Ravi
Hard
9.0
1 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
5.0
2 The Classic Weights & Scale
You have 8 lead marbles, one of which is heavier than the rest. What is the minimum amount of “weightings” (i.e. with a see-saw scale) you need to do to guarantee finding the odd one out?
Submitted by Valentin
Easy
3.0
1 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 3 Right or Left?
This is interesting. Look at the animation below. Do you see the girl spinning clockwise or counter-clockwise
Doable
4.0
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
4.7
1 2 Marble Weights
You are given a set of scales and 12 marbles. The scales are of the old balance variety. That is, a small dish hangs from each end of a rod that is balanced in the middle. The device enables you to c ...
Submitted by Ravi
Doable
6.0
0 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
2.8
2 1 What Am I?
Give me food, and I will live Give me water, and I will die What am I?
Submitted by Aakash
Doable
6.0
0 3 Cutting Numbers
When is Seven half of Twelve?
lateral thinking Submitted by Ravi
Doable
4.0
0 1 Plane In The Wind
An airplane flies in a straight line from airport A to airport B and back. It has constant engine speed and no wind. Will its total flight time increase, decrease or stay the same if throughout bot ...
Submitted by Valentin
Doable
4.0
1 1 Greatest Area
A farmer challenges an engineer, a physicist, and a mathematician to fence off the largest amount of area using the least amount of fence. The engineer made his fence in a circle and said it was th ...
Submitted by Valentin
Doable
3.3
2 The Number Problem
What does 3685=? 8809=6 7111=0 2172=0 6666=4 1111=0 3213=0 7662=2 8096=5 9312=1 4444=0 6824=3 9999=4 0345=1 2359=1 5522=0 9884=5 Enjoy, this is quite interesting.
Submitted by Ravi
Doable
3.3
1 1 Random Puzzle
Here’s something I heard from a friend, I thought it was appropriate. What do you call a 4 foot tall fortune teller who is wanted by the law? Good luck.
riddle funny Submitted by Ravi
Hard
8.0