What are some classic lateral thinking puzzles, and where can I find more?

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 fr helle K”pfe  ISBN 3-405-14796-4

For further information or feedback contact PSloane@Mathsoft.com