Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.
5 5 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
Doable
3.6
21 10 Odd Pills
Your pharmacist gives you 5 jars filled with pills. The pills contained in each jar have an identical appearance and size (i.e. if you mixed all of the pills you wouldn't be able to tell them apart). ...
Doable
3.6
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
3.5
5 7 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?
Doable
3.5
5 3 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
5 6 12 balls part 2
You have 12 identical RUBBER balls each of 10 grams and one of 9 grams.You have three weighs of a weighing machine (not a balance scale) to determine which ball is different and whether it is heavier o ...
Submitted by Vishal barot
Doable
3.3
3 3 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
3.3
1 2 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
3.3
10 8 Sum of Two Prime Numbers
If p, q > 2 are consecutive in set of primes. Since p,q can only be odd number, (p+q) is an even number. Can (p+q)/2 be prime? from http://republicofmath.com/
Submitted by MoralMachine
Easy
3.2
4 3 Don't Hang Yourself
A fool wants to tie a rope around the earth. So he buys a rope of 40,000 KM and ties it around the world. His neighbour, also a fool, wants to do the same only he wants the rope on sticks 1 meter abo ...
Easy
3.1
3 4 Ball Drop
A man is floating in a hot air balloon off the coast of Ireland. In one hand he has a bowling ball, and in the other a golf ball, and he drops them both over the side at the same time. which one ...
Easy
3.1
4 2 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
7 8 Clock Works - 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?
Easy
3.1
11 4 Measuring Up
You have a 3 and a 5 litre water container, each container has no markings except for that which gives you its total volume. You also have a running tap. You must use the containers and the tap in su ...
logic brain teaser Submitted by Ravi
Easy
3.1
1 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
3.0