Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
0 1 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 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
Doable
4.0
0 1 My eyes
My eyes fold like telescopes and view the world like periscopes Who am I? For a hint you should know I run really slow and walk as fast as i can. Do you know who I am?
Submitted by Aakash
Doable
6.0
1 Running Race
Phil and Sal race each other for 100 yards. Sal wins by 10 yards. They decide to race again, but this time, to even things up, Sal begins 10 yards behind the start line. Assuming that both run with t ...
Submitted by Aakash
Doable
6.0
0 1 Don't be a Square
Shown is a large square made up of four shapes, and a separate square, labeled with an E. Using all five of the shapes (A through E) only once, can you form a second perfect square?
Submitted by Aakash
Doable
6.0
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
6.0
0 Classic Knights & Knaves
Raymond Smullyan has made a career of writing logic problems. His most famous have to do with a mythical island of Knights and Knaves. Knights always tell the truth, and Knaves always lie. As you a ...
Submitted by Ravi
Doable
6.0
1 The Bookworm
Looking onto a shelf you see three books each labeled Volume 1, Volume 2, and Volume 3 respectively. Each book is 2.5 inches thick; that is the pages are 2 inches, and each cover .25 inches. A bo ...
Submitted by Aakash
Doable
6.0
0 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
4.0
0 What is Sammy exactly?
Police! Police! She cried, Police! he died! Sammy was my friend. If this is the end and i wont see him again, let me give just a kiss. Sammy was my friend. Down the roar he shall slide turning ro ...
Submitted by Aakash
Doable
6.0
0 The Twiddled Bolts
Two identical bolts are placed so that their helical grooves intermesh. If you move the bolts around each other as shown in the picture, would they a) move inward b) move outward c) remain the same d ...
Submitted by Valentin
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
Doable
6.0
0 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
Doable
6.0
0 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
0 Surgery
A boy and his father get into an enormous and unfortunate car accident. The father is taken to one hospital and the son to another. The boy’s surgeon walks into the hospital room and says “I cannot ...
Submitted by Valentin
Doable
6.0