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National Puzzle Day: Can you solve these 10 difficult brainteasers?
On National Puzzle Day, we take a look at ten fiendishly difficult riddles on the internet, can you solve them?
Are you a problem solver? Have you got the brainpower to solve these fiendishly difficult puzzles? Scroll down to find out.
On National Puzzle Day, we’ve collated some of the trickiest brainteasers for you to solve.
Looking for more brainteasers and puzzles? Visit puzzles.telegraph.co.uk and view our wide range of crosswords and sudoku puzzles.
10. Sudoku
The Everest of numerical games, dubbed the world’s hardest Sudoku puzzle, was published by Arto Inkala, a Finnish mathematician.
Can you solve it? Click to flip and reveal the answer ...
9. The 'world's hardest logic puzzle
There's no escape from this green-eyed logic puzzle....
Did you give up? Here's the answer ...
8. Einstein’s riddle
When Einstein wrote this riddle he apparently said that 98% of the world would not be able to solve it:
There are 5 houses in five different colours.
In each house lives a person with a different nationality.
These five owners drink a certain type of beverage, smoke a certain brand of cigar and keep a certain pet.
No owners have the same pet, smoke the same brand of cigar or drink the same beverage.
The question is: Who owns the fish?
Hints
The Brit lives in the red house
The Swede keeps dogs as pets
The Dane drinks tea
The green house is on the left of the white house
The green house's owner drinks coffee
The person who smokes Pall Mall rears birds
The owner of the yellow house smokes Dunhill
The man living in the centre house drinks milk
The Norwegian lives in the first house
The man who smokes blends lives next to the one who keeps cats
The man who keeps horses lives next to the man who smokes Dunhill
The owner who smokes BlueMaster drinks beer
The German smokes Prince
The Norwegian lives next to the blue house
The man who smokes blend has a neighbour who drinks water
Here's the answer:
7. The George Boolos puzzle
Can you solve this riddle? It was created by US logician George Boolos shortly before his death in 1996.
“Three gods A, B, and C are called, in no particular order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language, in which the words for yes and no are da and ja, in some order. You do not know which word means which.”
Here’s the simple solution...
6. Can you work out what spot this car is parked in?
Here's the answer...
5. When is Cheryl's birthday?
Cheryl and her birthday caused a furore after a confusing question involving two characters named Bernard and Albert went viral.
Cheryl gives her new friends, Albert and Bernard, ten possible dates to choose from when they enquire about her date of birth. She then tells Albert the month and Bernard the day of her birthday.
4. What way is the ballerina spinning?
This was created by Japanese Web designer Nobuyuki Kayahara. Which way do you think the ballerina is spinning?
Here's the answer.
3. Love in Kleptopia
"Jan and Maria have fallen in love (via the internet) and Jan wishes to mail her a ring. Unfortunately, they live in the country of Kleptopia where anything sent through the mail will be stolen unless it is enclosed in a padlocked box. Jan and Maria each have plenty of padlocks, but none to which the other has a key. How can Jan get the ring safely into Maria’s hands?"
Find the answer here at point 5.
2. The GCHQ Christmas quiz
Can you solve the puzzles that have stumped the world? This GCHQ Christmas puzzle has left thousands stumped.
Here's our solution.
1. Two spirals
Here's the answer.
Exam questions that divided the internet
Hannah's Sweets
When is Cheryl's birthday?
The answer
Step 1: Take the words from the question, and write it down as an equation - 6/n x 5/(n-1) = 1/3 Step 2: Multiply the 6 by the 5 and the n by the n-1. That gives you: 30/(n^2 - n) = 1/3 Step 3: Multiply the top-left by bottom-right and top-right by bottom-left Step 4: Subtract 90 from both sides, leading to your answer n^2 - n - 90 = 0
When is Cheryl's birthday?
The answer
You should create a table of four columns with the months at the top and the dates Cheryl gives after. "You can rule out some of the options. For Albert to have known the answer, he would have to have May and June as that is when 19 or 18 occur." The number 14 is the only one in both months but Bernard is now sure of the birth date. This means Bernard knows it is July 16.
The cruel exam question
The answer
The answer depends on what type of person you are. "In reality, if too many people overuse a common resource then everyone in the group suffers," said the professor who set it.
Why 5+5+5 doesn’t always make 15
The answer
A student was marked down for using the solution 5+5+5, with the teacher noting the correct working out should be shown as 3+3+3+3+3 using the repeated addition strategy.
The 50 cent conundrum
The answer
360 degrees in a circle divided by 12 x 2 coins = 60
Example questions from the 'hardest test in the world'
- Did the left or right win the twentieth century?
- "Secure people dare". Do they?
- Should intellectuals tweet?
- Should prisoners be allowed to watch television?
- How can words be beautiful?
- Can we be forced to be free?
- Is the financial sector larger than it should be?
- Can policy rely on human rationality?
- Is there an economic case for limiting pay bonuses to twice an annual salary?
- Should the state restrict what people should do with their pension savings?
- Is homelessness a reflection of a badly functioning economy?
- Would an inflation target of 4% be better than 2%?
- How do apologies work?
- Does the status quo have any moral privilege?
- Can emotions be reasons for decisions?
- Can there be substantive disagreement in the absence of fact?
- What is the connection between knowing something and being certain of it?
- Is meaning best understood via the concept of truth?
- How can someone know what they will do tomorrow if they do not know that they will not have a heart attack before tomorrow arrives?
- Who should pay for the costs of educating and bringing up children?