7 Interview Brainteasers and How You Should Be Answering Them (to get the job!)

7 Interview Brainteasers and How You Should Be Answering Them (to get the job!)

…and then, the interviewer leans toward you with a slight smirk on their face…you feel a little tremor of worry…why do they look so shifty and smug?

Slowly clearing their throat, they turn, look you straight in the eye and ask…

“If you were shrunk to the size of a pencil and put in a blender, how would you get out?”

What the hell…?! I must have misheard? How the hell am I supposed to answer? I wish I was in that blender right now! Thoughts…retreating…PANIC!!!

We’re not big fans of interview brainteasers either.

(In fact, in a recent blog for our business clients, we outwardly discredited their suitability for interview.)

These mind-boggling questions rose to popularity during the last decade and it’s very hard to see why!

In fact, even Google (notorious brain-teasing advocates during their heyday) have now brandished them as ‘a complete waste of time.’

But, you can’t teach an old dog new tricks as it were and some interviewers are still hypnotised by the the brainteaser and all it’s sparkles!

So this week, we’re breaking them down to give you a fighting chance…

Why do interviewers use brainteasers?

Some bright spark created interview brainteasers to assess candidates on the following key skills…

– Problem Solving. Can you at least attempt to solve problems as they arise?

– Analysis. Can you look at the big picture, analysing all available information to find a solution?

– Creativity. Do you think outside the box, or are you constrained by the rules?

– Performance under pressure. Can you keep it together in the face of ridiculous, stressful questions?

Asking questions that have no relevance…sounds like a great idea – right?

We’ll let you decide.

Recruiter Pro Tip

Not all interviews will include brainteasers. Like we said, we find them unnecessary and we’re not the only ones!

Often you’ll just need to prepare for regular questions, like the ones in our recent blog: 10 Typical Interview Questions and How to Answer Them.  

But larger, successful (often tech) companies who tend to get an overflow of applications per job do often use them.

They’re searching for the superstar staff; those who can really think on their feet.

Let us break them down for you…

The Pizza Puzzle.

Q1.  “If you were a pizza delivery man, how would you benefit from scissors?”

This little gem is attributed to Apple Inc and there clearly isn’t a right or wrong answer.

It’s a classic hypothetical puzzle, checking your ability to critically assess a situation you’ve never been in before and make well-formed deductions and arguments based on the available information.

You should…

  • Think the question through.
  • Thoroughly explain all of your reasoning.

For example, ‘It can be really frustrating for customers when they receive pizzas that aren’t cut up properly, so I’d use my trusty scissors to solve the problem should anyone be dissatisfied!”

It may sound ridiculous, but at least you’ve thought the question through and exhibited sound, well-argued reasoning. Click here to read more weird and wonderful answers.

You shouldn’t…

  • Get frustrated with the interviewer. They make the rules! You’re there to play the game.
  • Just blurt out an answer. This could come across lazy and disinterested.

Of course, if you wanted to be a little bit clever you could instead outline the reasons why you shouldn’t carry scissors with you on the job, for example, “its against health and safety” or “its an unnecessary implement.”

A Calculated Question.

Q2.  “How would you test a calculator?”

This is a fairly ambiguous question, attributed to IBM and I’m going to assume that you’ve never had to test a calculator before…

Recruiter Pro Tip

If an interviewer asks you a question that you don’t understand, don’t be afraid to clarify it.

Ask yourself, have they really given me all of the information I need?

In the example above, do you even know if they’re talking about the functionality of the calculator (the buttons) or the actual mathematical ability?

You should…

  • Take your time and make notes if you have to. It’s a tricky question; slow and steady will win the race.
  • Come up with a detailed and strategic method of testing the calculator.

Here is one possible answer to the question, thanks to eHow (yes, I’m cheating!)

  1. Enter this magic number, 370, into your computer. Multiply it by 3. The computer total should show 1110.
  2. Enter 370 into your computer once again. Multiply it by 6. The computer total should show 2220.
  3. Enter 370 into your computer a third time. Multiply it by 9. The computer total should show 3330.
  4. Enter 370 into your computer a fourth time. Multiply it by 12. The computer total should show 4440.
  5. Realise that multiplying 370 by a number divisible by 3 will produce a total that has the multiple of three as its first 3 digits. For example, 27 is 9 threes, if you multiply 370 by 9, the result is 9990.

You shouldn’t…

  • Rush your answer. If the method you come up with isn’t systematic, the interviewer could consider it as a reflection of your organisational and management skills.
  • Just guess. Remember, it’s perfectly fine to ask for extra clarification, if you’re struggling to understand the question.

Apples and Pears.

Epic Systems are to blame for this epic interview question:

Q3.  “An apple costs 40 cents, a banana costs 60 cents and a grapefruit costs 80 cents.  How much does a pear cost?”

Hats off if you’ve managed to work out the answer to this one (without taking a sneak peak below)!

It’s all about the vowels…

“If you charge 20 cents per vowel, the two-vowel word ‘apple’ would cost 40 cents, three-vowel ‘banana’ 60 cents, and four-vowel ‘grapefruit’ 80 cents. Therefore, a pear would cost 40 cents.”

Clever – right..?

You should…

  • Answer the question correctly, if you can; it would be incredibly impressive in this case!
  • Come up with a sensible answer, with a clear explanation. That should give you some brownie points at least!
  • Be as creative as you like!

You shouldn’t…

  • Blurt out an answer, without thinking. The interviewer will assume you’ve either heard the question before or that you can’t be bothered to consider it thoroughly.

The Farmer, the Fox and the Hen.

Q4.  “A farmer needs to cross the river with his chicken, a sack of corn and a fox.

His boat unfortunately only fits himself and one other thing.

The fox and chicken are hungry, so if he leaves the fox with the chicken, the chicken will get eaten, whilst if he leaves the chicken with the corn, the corn will get eaten.

How will the man get safely across with all 3?”

Do you recognise this question? Could you spontaneously answer it?

This is a really common brainteaser and is often utilised during group activities to assess how well you work as part of a team, to solve a problem.

The answer is simple, when you know it:

The man takes the chicken across and then goes back for the fox.

He can’t leave the fox and chicken together so when he drops the fox off, he picks up the chicken.

He then goes back for the corn. He can’t leave the corn and the chicken together so when he picks up the corn, he drops off the chicken.

When the corn is safely with the fox on the right side of the river, he goes to collect the chicken.

Of course, the real question is: why is the farmer hanging around with a fox in the first place? Very Suspicious.

You should…

  • Show the interviewer that you’re considering each element of the puzzle and then test your theories; they’ll like to see how you actually go about the problem-solving process.
  • Tell the interviewer if you’ve already faced this task before and can remember the answer.
  • Try to position yourself as the leader in group tasks. Facilitate the discussion, take into account everyone’s opinion and openly try to steer the team towards a conclusion.

You shouldn’t…

  • Rattle off the answer. It’ll show that you’ve heard it all before and you’ll come across just a little bit cocky.
  • Forget any crucial parts of the question (for example, letting the chicken cross with the corn). It’ll show interviewers that you might have issues with listening and critical thinking.
  • Overpower others in group tasks. Everyone deserves a chance to talk and you’ll just come across as arrogant and too dominant if you don’t allow others to speak.

Number Crunchers

Q5. “How many potatoes (in kg) does McDonald’s sell in a year in the UK?”

There are hundreds of variations on this Oliver Wyman interview question, most likely to crop up if the job vacancy requires mental arithmetic or mathematical ability.

How many square feet of pizza are eaten in the UK every year?

How many gas stations are there in the US?

How many pennies, if placed on top of each other, would it take to reach the top of Big Ben?

The answer is roughly 200 million kg of potatoes, but don’t worry, it’s highly unlikely that they’ll expect you to get the exact number!

I mean who would?

You should…

• Show off your mathematical skills. This is your chance to sell yourself, so even if your assumptions are completely off, outwardly show that you at least know how to add up!

• Take your time. One little mathematical slip up could reflect badly!

You shouldn’t…

• Do all of the maths in your head; they’ve asked the question to assess your mathematical ability and they won’t be able to do that if you simply offer them an answer with no explanation.

• Be hasty. Unthoughtful answers will betray your disinterest in the interviewer’s question.

Are you easily distracted?

Q6.  “Tracy’s mother had 4 children. The first child was named April, the second was named May, the third was named June. What was the fourth child called?”

What would your answer be? July? Or did you work out the sneaky little plot twist within?

This cruel interview brainteaser depends on its capacity to draw the listener’s attention away from the answer, focusing on the unimportant information.

Really – the question has already revealed the answer; ‘Tracy’s mother had 4 children.’ The fourth child must be called Tracy!

The names April, May and June meant nothing.

You should…

  • Get the correct answer! If you hear the question correctly and take enough time to consider it then eventually you should have a “Eureka” moment.

You shouldn’t…

  • Get the incorrect answer! Commonly, candidates will panic and answer ‘July’ or, having missed the reference to Tracy, try and be a bit too clever and answer ‘we can’t know. It’s probable that the fourth child is called July, but we can never know for sure.’

Both answers are just wrong!

A Classic Conundrum

Q7.  “How do you know if the light inside the fridge is on or off?”

This, somewhat philosophical, interview question has been attributed to Schlumberger.

You should…

Answer the Question!

There are a variety of ways to answer this question, some great and some not so great…

  • Use a camera
  • Drill a hole in the fridge door.
  • Find the sensor and test it with your thumb.
  • Touch the light bulb and see if it’s warm (be careful with this one, though!)

Although varying in practicality, all of the above at least genuinely answer the question!

You shouldn’t…

Give no answer at all.

Unlike some of our brainteasers, this question is fairly easy to answer; you certainly don’t have to have any technical knowledge or special skills.

If you have no answer whatsoever (no matter how outrageous) it shows a lack of creativity!


Brainteasers could be about any topic you might imagine and could crop up during any stage of the interview, so it’s very important to be prepared.


  • Think every question through thoroughly.
  • Explain your reasoning to the interviewer.
  • Slow and steady wins the race.
  • Think strategically.
  • Answer correctly, if you can!
  • Be creative.
  • Don’t be afraid to ask follow up, clarification questions.

Of course, unfortunately they’re not the only type on nightmare questions you’ll come across; many interviewers like to throw in left-field questions to put candidates off their game.

Of course, you could always get your own back at the end of your interview, asking a whole host of more difficult questions for your interviewer!

For inspiration, check out our other recent blog: 7 questions you should ask to impress your interviewer. 

Good Luck!

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