Paul Sloane's list of Classic Lateral Thinking Puzzles

Lateral thinking puzzles are often strange situations which require an explanation. They are solved through a dialogue between the quizmaster who sets the puzzle and the solver or solvers who try to figure out the answer. The puzzles as stated generally do not contain sufficient information for the solver to uncover the solution. So a key part of the process is the asking of questions. The questions can receive one of only three possible answers - yes, no or irrelevant.

When one line of enquiry reaches an end then another approach is needed, often from a completely new direction. This is where the lateral thinking comes in.

Some people find it frustrating that for any puzzle it is possible to construct various answers which fit the initial statement of the puzzle. However, for a good lateral thinking puzzle, the proper answer will be the best in the sense of the most apt and satisfying. When you hear the right answer to a good puzzle of this type you should want to kick yourself for not working it out!

This kind of puzzle teaches you to check your assumptions about any situation. You need to be open-minded, flexible and creative in your questioning and able to put lots of different clues and pieces of information together. Once you reach a viable solution you keep going in order to refine it or replace it with a better solution. This is lateral thinking!

This list contains some of the most renowned and representative lateral thinking puzzles as well as some of those which crop up most frequently on the rec.puzzles newgroup.

A. The Puzzles

1. The man in the Elevator

A man lives on the tenth floor of a building. Every day he takes the elevator to go down to the ground floor to go to work or to go shopping. When he returns he takes the elevator to the seventh floor and walks up the stairs to reach his apartment on the tenth floor. He hates walking so why does he do it?

This is probably the best known and most celebrated of all lateral thinking puzzles. It is a true classic. Although there are many possible solutions which fit the initial conditions, only the canonical answer is truly satisfying.

2. The Man in the Bar

A man walks into a bar and asks the barman for a glass of water. The barman pulls out a gun and points it at the man. The man says 'Thank you' and walks out.

This puzzle has claims to be the best of the genre. It is simple in its statement, absolutely baffling and yet with a completely satisfying solution. Most people struggle very hard to solve this one yet they like the answer when they hear it or have the satisfaction of figuring it out.

3. The Man who Hanged Himself

Not far from Madrid, there is a large wooden barn. The barn is completely empty except for a dead man hanging from the middle of the central rafter. The rope around his neck is ten feet long and his feet are three feet off the ground. The nearest wall is 20 feet away from the man. It is not possible to climb up the walls or along the rafters. The man hanged himself. How did he do it?

4. Death in a Field

A man is lying dead in a field. Next to him there is an unopened package. There is no other creature in the field. How did he die?

5. Anthony and Cleopatra

Anthony and Cleopatra are lying dead on the floor of a villa in Egypt. Nearby is a broken bowl. There is no mark on either of their bodies and they were not poisoned. How did they die?

6. The Coal, Carrot and Scarf

Five pieces of coal, a carrot and a scarf are lying on the lawn. Nobody put them on the lawn but there is a perfectly logical reason why they should be there. What is it?

7. Trouble with Sons

A woman had two sons who were born on the same hour of the same day of the same year. But they were not twins. How could this be so?

8. Push that Car

A man pushed his car. He stopped when he reached a hotel at which point he knew he was bankrupt. Why?

9. The Arm of the Postal Service

One day a man received a parcel in the post. Carefully packed inside was a human arm. He examined it, repacked it and then sent it on to another man. The second man also carefully examined the arm before taking it to the woods and burying it. Why did they do this?

This one probably has more variations than any other. A great one to puzzle out. It requires plenty of good questions.

10. Heaven

A man died and went to Heaven. There were thousands of other people there. They were all naked and all looked as they did at the age of 21. He looked around to see if there was anyone he recognised. He saw a couple and he knew immediately that they were Adam and Eve. How did he know?

11. Friday

A man rode into town on Friday. He stayed for three nights and then left on Friday. How come?

A silly one - but it is surprisingly popular.

12. Manhole Covers

Why is it better to have round manhole covers than square ones?

This is logical rather than lateral, but it is a good puzzle which can be solved by lateral thinking techniques. It is supposedly used by a very well-known software company as an interview question for prospective employees.

13. The Deadly Party

A man went to a party and drank some of the punch. He then left early. Everyone else at the party who drank the punch subsequently died of poisoning. Why did the man not die?

14. The Deadly Dish

Two men went into a restaurant. They both ordered the same dish from the menu. After they tasted it, one of the men went outside the restaurant and shot himself. Why?

15. The Realization

A man was walking downstairs in a building when he suddenly realized that his wife had just died. How?

16. The Blind Beggar

A blind beggar had a brother who died. What relation was the blind beggar to the brother who died? (Brother is not the answer).

17. The Broken Match

A man is found dead in a field. He is clutching a broken match. What happened?

18. The Music Stopped

The music stopped. She died. Explain.

19. Swimmer in the Forest

Deep in the forest was found the body of a man who was wearing only swimming trunks, snorkel and facemask. The nearest lake was 8 miles away and the sea was 100 miles away. How had he died?

This is supposedly based on a true incident. Does this make it an urban legend? Many urban legends can be restated as lateral thinking puzzles. This is a very good one of this type.

20. The Elder Twin

One day Kerry celebrated her birthday. Two days later her older twin brother, Terry, celebrated his birthday. How come?

B. Answers and Comments

1. The man in the Elevator

The man is (of course) a dwarf. Variants of this puzzle include the clue that on rainy days he goes up in the elevator to the tenth floor (he uses his umbrella!)

2. The Man in the Bar

The man had hiccups. The barman recognized this from his speech and drew the gun in order to give him a shock. It worked and cured the hiccups - so the man no longer needed the water.

The is a simple puzzle to state but a difficult one to solve. It is a perfect example of a seemingly irrational and incongruous situation having a simple and complete explanation. Amazingly this classic puzzle seems to work in different cultures and languages.

3. The Man who Hanged Himself

He climbed on a block of ice which has since melted.

This one is often stated with the clue of a puddle of water, but surely this is too much assistance. It is one of several problems which depend on the change of state of water (snow or ice to water or steam).

4. Death in a Field

The man had jumped from a plane but his parachute had failed to open. It is the unopened package.

This is sometimes given with the following rather elegant clue - as he approached the centre of the field he knew he was going to die. This is another of the top classics which is right up there with 'The Man in the Bar'. If the solver is thinking along the wrong lines (i.e. in the two dimensions of the ground) then the lateral jump to the third dimension can be tough to make.

5. Anthony and Cleopatra

Anthony and Cleopatra were goldfish whose bowl was knocked over by a clumsy dog.

This is one of a set of puzzles which deceive by using human names for animals. This is not a very satisfactory basis for a good puzzle but despite that, the puzzle has enduring popularity.

6. The Coal, Carrot and Scarf

They were used by children who made a snowman. The snow has now melted.

Another change of state puzzle. After this you should be on the look-out for them!

7. Trouble with Sons

They were two of a set of triplets (or quadruplets etc.)

This simple little puzzle stumps many people. They try outlandish solutions involving test-tube babies or surrogate mothers. Why does the brain search for complex solutions when there is a much simpler one available?

8. Push that Car

He was playing Monopoly.

9. The Arm of the Postal Service

The three men had been stranded on a desert island. Desperate for food, they had agreed to amputate their left arms in order to eat them. They swore an oath that each would have his left arm cut off. One of them was a doctor and he cut the arms off his two companions. They were then rescued. But his oath was still binding so he later had to have his arm amputated and sent to his colleagues.

This is often told with a further twist whereby a doctor pays a tramp a large sum in order to amputate the tramp's arm which the doctor then sends to another man who inspects it etc. This variation can make for a long night of questioning!

10. Heaven

He recognized Adam and Eve as the only people without navels. Because they were not born of women, they had never had umbilical cords and therefore they never had navels.

This one seems perfectly logical but it can sometimes spark fierce theological arguments!

11. Friday

The man's horse was called Friday.

OK, so this is really a schoolboy riddle but people keep asking it!

12. Manhole Covers

A square manhole cover can be turned and dropped down the diagonal of the manhole. A round manhole cannot be dropped down the manhole. So for safety and practicality, all manhole covers should be round.

13. The Deadly Party

The poison in the punch came from the ice cubes. When the man drank the punch the ice was fully frozen. Gradually it melted, poisoning the punch.

You were warned to be on the look-out for these ice puzzles!

14. The Deadly Dish

The dish that the two men ordered was albatross. They had been stranded many years earlier on a desert island. When the man tasted albatross he realized that he had never tasted it before. This meant that the meat he had been given on the island was not albatross as he had been told. He correctly deduced that he had eaten the flesh of his son who had died when they first reached the island.

This has something in common with No. 9 above but is in my opinion even better. It is fiendishly difficult to figure out from a standing start. A beautiful aspect of this problem is the subtle fact that he shot himself because he did not recognise the taste of the dish!

15. The Realization

The man had visited his wife in hospital. She was on a life-support machine. As he was walking down the stairs all the lights went out. There had been a power cut and the emergency back-up systems had failed. He knew that she had died.

16. The Blind Beggar

The blind beggar was the sister of her brother who died.

This puzzle is one of a type that depends on the listener making implicit assumptions about gender - in this case that a blind beggar is a man. Similar puzzles involve surgeons who refuse to operate on their sons etc. This is probably the best of the class because it is very simply stated and yet which has the power to baffle those who have not heard it before.

17. The Broken Match

He and a number of other passengers were making a balloon trip in a desperate attempt to flee a country. The balloon had to lose weight to stop it from crashing. He drew the short match and had to jump.

18. The Music Stopped

She was a circus tight-rope walker who walked blindfolded over a high wire. The band played as she crossed and when the music stopped it was the signal that she had reached the end of the walk and could safely alight. One day the conductor was taken ill and the stand-in conductor ended the piece of music too early. She stepped off to her death.

19. Swimmer in the Forest

During a forest fire, a fire-fighting plane had scooped up some water from the lake to drop on the fire. The plane had accidentally picked up the unfortunate swimmer.

20. The Elder Twin

At the time she went into labor, the mother of the twins was travelling by boat. The older twin, Terry, was born first early on March 1st. The boat then crossed the International Date line (or any time zone line) and Kerry, the younger twin, was born on February the 28th. In a leap year the younger twin celebrates her birthday two days before her older brother.

This puzzle was submitted to Games Magazine's 'How Come' competition in 1992 by Judy Dean. It won.

Reference Sources

If you enjoy this kind of puzzle (either solving or inflicting on others) then the following books (all published by Sterling at $4.95) are recommended:

Lateral Thinking Puzzlers by Paul Sloane 1991 ISBN 0-8069-8227-6 Contains 93 puzzles including most of the classics such as numbers 1 to 10 above.

Challenging Lateral Thinking Puzzles by Paul Sloane and Des MacHale? 1993 ISBN 0-8069-8671-9 Contains 91 puzzles including numbers 11 - 15 above and 30 Wally Test questions (sneaky catch questions).

Great Lateral Thinking Puzzles by Paul Sloane and Des MacHale? 1994 ISBN 0-8069-0553-0 Contains 93 puzzles including numbers 16 - 20 above and 20 Wally Test questions.

Test Your Lateral Thinking IQ by Paul Sloane 1994 ISBN 0-8069-0684-7 Endeavours to teach and measure lateral thinking skills using puzzles as tests. Contains 52 puzzles.

Improve your Lateral Thinking - Puzzles to Challenge your Mind by Paul Sloane and Des MacHale? 1995 ISBN 0-8069-1374-6 Contains 115 puzzles and 20 Wally Test questions

The above books are distributed by Cassell in the UK and by Capricorn Link in Australia.

The following translations are also available:

In Spanish published by Juegos &Co, Buenos Aires and Zugarto Ediciones, Madrid. Ejercicios de Pensamiento Lateral ISBN 84-88155-04-2 Nuevos Ejercicios de Pensamiento Lateral ISBN 84-88155-21-2

In Swedish published by Brain Books AB Mannen i hissen ISBN 91-88410-20-X De sex applena ISBN 91-88410-30-7

In German published by BLV, Munich Denkpuzzles fr helle Kpfe ISBN 3-405-14796-4

For further information or feedback contact PSloane@Mathsoft.com

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