Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.

Sort by:

All puzzles

 5 Troll Toll You are on your way to visit your Grandma, who lives at the end of the valley. It’s her birthday, and you want to give her the cakes you’ve made. Between your house and her house, you have to cross ... Submitted by Aakash Easy 2.7 5 Lab Rat on the Run Consider a lab rat in a maze. There are four paths that can be taken with equal probability. Path A leads to exit in 5 minutes. Path B leads back to start and takes 8 minutes. Path C leads to exit in 3 ... Submitted by Yiğit Oktar Doable 6.0 5 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? Submitted by Valentin Doable 3.5 5 Don't Eat Me! Would you rather a crocodile attack you or an alligator? Submitted by Aakash Doable 4.9 5 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 5 Cards With Crosses You have a stack of 23 cards. Each card has an image of a cross on one side, and an image of a circle on the other side. You know that 14 cards in the stack are laying with the cross up, and therefor ... Submitted by Valentin Doable 6.0 5 Birthday Problem (Classic) A classic problem. How many people do you need to have in a room so that the probability of at least 2 of people sharing a birthday is greater than 50%. Assume 365 days in a year (no leap years) ... Submitted by Valentin Hard 8.4 5 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 ... Submitted by Aakash Hard 7.7 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? Submitted by Valentin Doable 3.5 5 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 4.3 5 The Stealing Mailman This is a fairly simple problem that can cause some people trouble. Kevin and Sophia want to mail high confidential letters between each other. They know that the mailman is crooked and opens the le ... Submitted by Ravi Doable 6.5 5 Age of Three Kids One day, a guy from census come into a house. When he rings the bell, a lady comes out. He then asks how many people lives in her house, and their age. And then she says: I am 45 years old. I have thr ... Submitted by Rifqi Ardia Ramadhan Doable 6.0 5 Count The Bits Write a function that counts the number of bits in an integer that are set to 1 that is linear in time complexity in the worst case, but sub-linear on average. Submitted by Jay Elliott Hard 7.6 4 Electrical Deaths You and your friend are driving out in the pouring rain one night. It soon becomes much to hard too see, so you stop at closest house possible. When you knock on the door, an old lady welcomes you to ... Submitted by Ravi Doable 3.7 4 What am I? The first person makes me and sells me. The second person buys me but doesnt use me. The third person uses me but doesnt see me. What am I? Submitted by Valentin Hard 6.8