100 Brain Teasers With Answers, Sorted by How Hard They Are

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Girl laughing after solving a brain teaser

A good brain teaser feels unfair right up until the second it feels obvious. That flip is the whole point of it. The problem with most brain teaser lists is that they mix a riddle a six year old solves instantly with something that needs algebra, and you never know which one you are about to get. The questions are sorted honestly by difficulty. The warm ups really are warm ups. The last section will beat most people. Every answer sits directly under its question, so you can check yourself without scrolling to a key at the bottom and accidentally reading four answers on the way. If you are running these with a group, cover the screen and read them aloud. Half the fun is watching somebody land on the answer three seconds before everyone else and refuse to say it.

What you will find here

Warm up brain teasers

Start here. These are solvable in under a minute and they get people talking.

  1. What has to be broken before you can use it?
    An egg.
  2. I am tall when I am young and short when I am old. What am I?
    A candle.
  3. What month of the year has 28 days?
    All of them.
  4. What is full of holes but still holds water?
    A sponge.
  5. What question can you never answer yes to?
    Are you asleep yet?
  6. What goes up but never comes down?
    Your age.
  7. What has hands but cannot clap?
    A clock.
  8. What gets wetter the more it dries?
    A towel.
  9. What has a head and a tail but no body?
    A coin.
  10. What can you catch but not throw?
    A cold.
  11. What has one eye but cannot see?
    A needle.
  12. What has many keys but cannot open a single lock?
    A piano.
  13. What runs but never walks?
    Water.
  14. The more of it you take, the more you leave behind. What is it?
    Footsteps.
  15. What has a neck but no head?
    A bottle.
  16. What can travel around the world while staying in one corner?
    A stamp.

The 28 days one is the single best opener I know. People answer February with total confidence and then have to sit with it.

Lateral thinking puzzles

These are the ones where the answer is not hidden in the wording, it is hidden in an assumption you made without noticing. If you are stuck, ask yourself what you took for granted.

  1. A man lives on the tenth floor. Every morning he takes the lift down. Coming home he takes it to the seventh floor and walks the rest, except on rainy days, when he rides all the way. Why?
    He is short and can only reach the seventh floor button. On rainy days he has an umbrella to press the tenth.
  2. A player leaves home, makes three left turns, returns home and sees two masked people. Who are they?
    A catcher and an umpire at home plate.
  3. Two people are born at the same moment to the same mother, but they are not twins. How?
    They are two of a set of triplets.
  4. A man pushes his car to a hotel and tells the owner he is bankrupt. Why?
    He is playing Monopoly.
  5. A cowboy rides into town on Friday, stays three days, and rides out on Friday. How?
    His horse is named Friday.
  6. What can go up a chimney down but cannot go down a chimney up?
    An umbrella.
  7. A player pushes a car to a hotel and suddenly knows they are broke. Why?
    They are playing Monopoly.
  8. Forward I am heavy, backward I am not. What am I?
    The word ton.
  9. A doctor and a boy are fishing. The boy is the doctor’s son, but the doctor is not the boy’s father. Who is the doctor?
    His mother.
  10. How far can a dog run into the woods?
    Halfway. After that it is running out.
  11. A man leaves home, turns left three times, and returns home to find two masked men waiting. Who are they?
    The catcher and the umpire.
  12. If you have a match and enter a dark room with an oil lamp, a candle and a fireplace, which do you light first?
    The match.
  13. Some months have 31 days, some have 30. How many have 29?
    All of them, in a leap year.
  14. You are in a race and you overtake the person in second place. What position are you in?
    Second. You took their place, not the leader’s.

The photographer one is the classic for a reason. Nobody hears the word shoots and thinks about a camera, and that is exactly what the puzzle is built on.

Number and logic puzzles

Paper is allowed here. Some of these genuinely need it.

  1. A bat and a ball cost $1.10 together. The bat costs $1.00 more than the ball. How much is the ball?
    Five cents. Most people say ten, but then the bat would be $1.10 and the total $1.20.
  2. If it takes 5 machines 5 minutes to make 5 widgets, how long do 100 machines take to make 100 widgets?
    Five minutes. Each machine makes one widget in five minutes.
  3. A lily pad patch doubles in size every day and covers the lake on day 48. What day is it half covered?
    Day 47.
  4. You have two ropes that each burn for exactly one hour, but not evenly. How do you measure 45 minutes?
    Light rope one at both ends and rope two at one end. When rope one is gone, 30 minutes have passed. Light rope two’s other end. It burns out 15 minutes later.
  5. Three people pay $30 for a room. The clerk returns $5, the bellhop keeps $2 and gives them $1 each. They paid $9 each, which is $27, plus the bellhop’s $2 is $29. Where is the missing dollar?
    Nowhere. The $27 already includes the bellhop’s $2. Adding it again is the trick.
  6. A farmer must cross a river with a fox, a chicken and a bag of grain. The boat holds one item. Fox eats chicken, chicken eats grain. How?
    Take the chicken, return, take the fox, bring the chicken back, take the grain, return, take the chicken.
  7. You have 8 balls, one heavier. With a balance scale and two weighings, find it.
    Weigh 3 against 3. If balanced, weigh the last two. If not, take the heavy three and weigh one against one.
  8. What is the next number: 1, 11, 21, 1211, 111221?
    312211. Each line describes the one before it out loud.
  9. A clock strikes six in five seconds. How long to strike twelve?
    Eleven seconds. The gaps are counted, not the strikes, and six strikes has five gaps.
  10. If you have 3 apples and take away 2, how many do you have?
    Two. The ones you took.
  11. How many times can you subtract 10 from 100?
    Once. After that you are subtracting from 90.
  12. A snail climbs 3 feet a day up a 10 foot wall and slips 2 feet each night. How many days to the top?
    Eight. On day eight it climbs to 10 and is out before it can slip.

The bat and ball question has been given to thousands of university students and most of them get it wrong. If you said ten cents, you are in extremely normal company.

Word and letter puzzles

  1. What English word has three consecutive double letters?
    Bookkeeper.
  2. What word becomes shorter when you add two letters to it?
    Short.
  3. What five letter word becomes shorter when you add two letters?
    Short again, and yes, that is the joke.
  4. What starts with T, ends with T, and has T in it?
    A teapot.
  5. Which word in the dictionary is spelled incorrectly?
    Incorrectly.
  6. What word is pronounced the same if you remove four of its five letters?
    Queue.
  7. What has 13 hearts but no other organs?
    A deck of cards.
  8. Name a word that contains all five vowels in order.
    Facetious.
  9. What is the longest word typed with only the left hand on a keyboard?
    Stewardesses.
  10. What common word has the letters SS twice?
    Possession.
  11. I am a word of letters three. Add two and fewer there will be. What am I?
    Few.
  12. What word looks the same upside down and backwards?
    SWIMS.
  13. What seven letter word becomes longer when the third letter is removed?
    Lounger.
  14. What is the only word that ends in the letters MT?
    Dreamt.
  15. Which four letter word can be written forward, backward or upside down and still read the same?
    NOON.
  16. What word contains 26 letters but only has three syllables?
    Alphabet.
  17. Take away my first letter and I still sound the same. Take away my last and I sound the same again. What am I?
    Empty.
  18. What begins with an E, ends with an E, and usually has one letter in it?
    An envelope.
  19. What English word retains the same pronunciation when four of its five letters are removed?
    Queue, which leaves Q.
  20. What word is always spelled wrong in every dictionary?
    Wrong.

Picture-it-in-your-head teasers

No paper, no counting on fingers. These are the ones that fall apart if you try to hold too much of them at once.

  1. A rooster lays an egg on the peak of a barn roof. Which way does it roll?
    Neither. Roosters do not lay eggs.
  2. You are running a race and pass the person in last place. What position are you in?
    You cannot pass the person in last place. They would be behind you.
  3. A plane crashes on the border of two countries. Where do they bury the survivors?
    Survivors are not buried.
  4. How many birthdays does the average person have?
    One. The rest are anniversaries of it.
  5. If a red house is made of red bricks and a blue house of blue bricks, what is a greenhouse made of?
    Glass.
  6. Before Mount Everest was discovered, what was the tallest mountain in the world?
    Mount Everest. It did not grow when we noticed it.
  7. A farmer has 17 sheep and all but 9 run away. How many are left?
    Nine.
  8. Divide 30 by half and add ten. What do you get?
    Seventy. Dividing by half means multiplying by two.
  9. Two fathers and two sons went fishing and caught three fish, one each. How?
    They are a grandfather, a father and a son.
  10. What weighs more, a pound of feathers or a pound of bricks?
    Neither. Both weigh a pound.
  11. If you take two apples from three apples, what do you have?
    Two apples.
  12. A man builds a house with four walls, all facing south. A bear walks by. What colour is it?
    White. The house is at the North Pole.
  13. What can fill a room but takes up no space?
    Light.
  14. How much dirt is in a hole 3 feet deep and 2 feet wide?
    None. It is a hole.
  15. Which is heavier, 100 pounds of rocks or 100 pounds of nothing?
    The rocks, since nothing weighs nothing.
  16. You see a boat full of people but there is not a single person on board. How?
    Everyone on board is married.

I have watched a room of adults argue about the greenhouse one. Somebody always commits to green bricks and then has to walk it back.

Sequence and pattern teasers

Every one of these has a rule. Finding the rule is the puzzle.

  1. What comes next: 2, 3, 5, 9, 17?
    33. Double the number and subtract one.
  2. What comes next: J, F, M, A, M, J, J, A?
    S. They are the first letters of the months.
  3. What comes next: 1, 4, 9, 16, 25?
    36. They are square numbers.
  4. What comes next: O, T, T, F, F, S, S?
    E. First letters of one, two, three and so on.
  5. What comes next: 1, 1, 2, 3, 5, 8?
    13. Each number is the sum of the two before it.
  6. What comes next: 7, 14, 28, 56?
    112. Each is doubled.
  7. What comes next: Z, Y, X, W, V?
    U. The alphabet backwards.
  8. What comes next: 4, 6, 9, 13, 18?
    24. The gaps grow by one each time.
  9. What comes next: 100, 96, 89, 79?
    66. Subtract 4, then 7, then 10, then 13.
  10. Which number is the odd one out: 9, 16, 25, 36, 42?
    42. The rest are squares.
  11. What comes next: 3, 6, 11, 18, 27?
    38. Add 3, 5, 7, 9, then 11.
  12. What comes next: M, V, E, M, J, S?
    U. The planets in order from the sun.

Brain teasers that beat most people

This is the section I would use if I wanted to end an argument about who is the smartest person in the room.

  1. You have two doors, one to a prize and one to an empty room, and two guards, one who always lies and one who always tells the truth. You get one question. What do you ask?
    Ask either guard which door the other guard would say leads to the prize, then pick the opposite one.
  2. Three switches outside a room control three bulbs inside. You may enter once. How do you know which is which?
    Turn on the first for ten minutes and switch it off. Turn on the second and go in. Lit is the second, warm is the first, cold is the third.
  3. You have 100 coins, 10 heads up, in the dark. Split them into two piles with equal heads.
    Take any 10 coins into a new pile and flip all of them.
  4. A man has a 3 litre and a 5 litre jug. How does he measure exactly 4 litres?
    Fill the 5, pour into the 3 leaving 2. Empty the 3, move the 2 across, fill the 5 again and top up the 3, which takes 1, leaving 4.
  5. Five players split 100 coins by seniority. Each proposes a split and leaves the game if the vote fails. What does the first propose?
    Keep 98 and give 1 each to the third and fifth players, who would otherwise receive nothing in the next round.
  6. You are on an island where everyone with blue eyes must leave at midnight once they know their own eye colour. A visitor says ‘I see someone with blue eyes.’ What happens?
    If there are n blue eyed people, they all leave on night n. The statement gives everyone a shared starting point to count from.
  7. A prisoner is offered 100 white and 100 black marbles in two bowls, and picks one bowl then one marble blind. How does he maximise his odds of white?
    Put one white marble alone in a bowl and the other 199 in the second. That gives about 75 percent.
  8. How many times a day are the hands of a clock exactly on top of each other?
    22 times, not 24. They overlap 11 times in each 12 hour cycle.
  9. Monty Hall shows you three doors, one hides a car. You pick one, he opens a different door showing a goat, and offers you a switch. Should you?
    Yes. Switching wins two thirds of the time.
  10. You have 12 balls, one is a different weight but you do not know which way. Find it in three weighings.
    Weigh 4 against 4, then use the result to split the suspect group of 4 or the known-normal 4 against the remaining 3 and 1, comparing against balls you have already proven normal.

If you get the blue eyes one on first reading without help, I would genuinely like to know. It took me two attempts and a diagram.

More jokes to try next

Before you go

The best way to use this page is to not read the answers. Pick five, sit with them for a day, and let them annoy you. A brain teaser you solve on your own is worth about ten you read the answer to, which is inconvenient advice on a page that puts every answer right under the question.

Questions people ask

What is the difference between a brain teaser and a riddle?

A riddle usually hides its answer in wordplay, and a brain teaser usually hides it in logic. In practice the two overlap so much that most lists, including this one, contain both.

Are brain teasers good for kids?

The first two sections work well from about age eight. The number puzzles and the last section are aimed at teenagers and adults.

What is the hardest brain teaser here?

The blue eyes island puzzle. It looks like it contains no new information and it does, which is what makes it hard to accept.

Do brain teasers actually improve your thinking?

There is no strong evidence they make you smarter in general. They are good practice at noticing your own assumptions, which is a narrower but real skill.

Can I use these in a classroom or a meeting?

Yes, and the warm up section is built for exactly that. One teaser at the start of a session works better than ten at once.


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