Brain Teasers for Adults — Challenge Your Mind

What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have 1 letter left. What is the word?

Three gods A, B, and C are called True, False, and Random, in some order. True always speaks truly, False always speaks falsely, and Random speaks truly or falsely at random. Determine the identities of A, B, and C by asking three yes-or-no questions, each addressed to one god.

You have 12 identical-looking balls and a balance scale. One ball is a different weight (heavier or lighter). You have only three weighings to determine which ball is different and whether it is heavier or lighter.

What is special about the number 8,549,176,320?

I am a word of six letters. My first three letters refer to an automobile. My last three letters refer to a household animal. My first four letters is a fish. My whole is found in your room. What am I?

You have two identical eggs and access to a 100-story building. You need to figure out the highest floor from which an egg can be dropped without breaking. What's the minimum number of drops needed in the worst case?

There are three boxes: one with only apples, one with only oranges, and one with both. All labels are wrong. You can pick one fruit from one box. How do you label all boxes correctly?

You're in a dark room with a candle, a wood stove, and a gas lamp. You only have one match. Which do you light first?

If you wrote all the numbers from 1 to 100, how many times would you write the digit 9?

In a certain country, half of 5 is 3. Based on the same proportion, what is one-third of 10?

There are 100 lockers in a hallway, all closed. 100 students walk by one at a time. The first student opens every locker. The second student closes every 2nd locker. The third student toggles every 3rd locker. This continues for all 100 students. Which lockers are open at the end?

A windowless room contains three identical light fixtures, each containing an identical light bulb. Each light is connected to one of three switches outside the room. You may manipulate the switches however you wish, but once you open the door, you cannot touch the switches again. How do you determine which switch controls which light?

Two ropes each take exactly one hour to burn from end to end, but they burn at non-uniform rates. How can you measure exactly 45 minutes?

Five people were eating apples. A finished before B but behind C. D finished before E but behind B. What was the finishing order?

I turn polar bears white and I will make you cry. I make guys have to pee and girls comb their hair. I make celebrities look stupid and normal people look like celebrities. I turn pancakes brown and make your champagne bubble. What am I?

A lily pad doubles in size every day. On day 30, it covers the entire lake. On what day did it cover half the lake?

You have a 3-gallon jug and a 5-gallon jug. How do you measure exactly 4 gallons?

You are in a room with two doors. One leads to freedom and one leads to death. There are two guards — one always tells the truth and one always lies. You don't know which is which. You can ask one guard one question. What do you ask?

You're on a game show. Behind one door is a car; behind the other two are goats. You pick door 1. The host, who knows what's behind each door, opens door 3 (revealing a goat). Should you switch to door 2?

A prisoner is told: 'If you tell a lie, we will hang you. If you tell the truth, we will shoot you.' What does the prisoner say to survive?

What common English word is nine letters long, and each time you remove a letter, it still forms a valid English word, down to a single letter?

How many times can you subtract 5 from 25?

An airplane crashes on the border of the US and Canada. Where do they bury the survivors?

Three missionaries and three cannibals must cross a river using a boat which can carry at most two people. If cannibals ever outnumber missionaries on either bank, the missionaries will be eaten. How do they all get across?

A man is looking at a photograph of someone. His friend asks who it is. The man replies, 'Brothers and sisters, I have none. But that man's father is my father's son.' Who is in the photograph?

A girl has as many brothers as sisters, but each brother has only half as many brothers as sisters. How many brothers and sisters are there in the family?

A woman shoots her husband, then holds him underwater for five minutes. Next, she hangs him. But five minutes later they both go out and enjoy a wonderful dinner. How?