Simple Software for Better Interview Skills

Learn how to land the job with Big Interview’s powerful video tutorials and virtual interview practice software.

How to Answer Brainteaser Interview Questions

Posted by

Egg Head

Do job seekers still need to worry about brainteaser interview questions?

While brainteaser questions are no longer trendy, some companies still rely on them. Read up on these challenging questions and be prepared in case you run into one.

Google and the History of the Brainteaser

Da Vinci
In the past, Google and other top companies were known for challenging applicants with interview brainteasers, but these questions have lately fallen out of popularity.

In a recent interview with The New York Times, Laszlo Bock, senior vice president of people operations for Google, said, “On the hiring side, we found that brainteasers are a complete waste of time.”

His take is that that candidates’ answers to brainteasers don’t predict anything. In fact, he says that structured behavioral interviews are now Google’s hiring tool of choice.

Note: We agree that behavioral questions tend to be more effective and most hiring companies ask behavioral questions these days, so make sure that you prepare to answer them (Read: Behavioral Interview Tips).

Gareth McLeod, a software engineer who worked at Facebook and has interviewed with a “who’s who of Silicon Valley companies,” says Google is not alone.

“Brainteaser questions are significantly less common now than when I started interviewing 6-ish years ago,” McLeod says. “Google, Facebook, Apple, and the other high-quality software companies have phased them out over the last few years. Google’s announcement of the last week was really just a message to other companies to stop doing it as well.”

Okay, so brainteaser questions are no longer trendy or innovative. However, many companies are still using them. These questions are most common in interviews for entry-level and junior positions that require analytic and problem solving skills (including jobs in technology, finance, engineering, and consulting).

What do we mean by brainteaser questions?

Da Vinci
There is some confusion around the definition of “brainteaser question.” When I reached out to my network for brainteaser question examples, most people responded with questions that are simply difficult, but not really brainteasers.

So let’s go to Dictionary.com. The definition of brainteaser is “a puzzle or problem whose solution requires great ingenuity.”

There are many questions that are challenging that are NOT brainteasers. These include tough technical questions, questions about your values, questions about failures or weaknesses, and others.

With a brainteaser question, the focus is on a puzzle or problem.

Why do companies ask brainteaser questions?

Da Vinci
Interviewers ask brainteaser questions because they think your ability to answer will provide some indication of your ability to do the job. Often, the hiring manager feels the brainteaser will help them to evaluate your strength in one or more of the following competency areas:

Problem solving — Can you quickly analyze a problem and devise a solution?
Critical thinking — Can you see the big picture, think clearly, evaluate options?
Analytic skills — Can you analyze data, determine probability, make calculations?
Creativity — Do you take an innovative approach to problems?
Ability to think on your feet — Can you “wing it” without preparation or structure?
Ability to perform under pressure — Can you stay cool and logical under stress?

The interviewer is most interested in your approach to the brainteaser and how you think. The actual answer is often irrelevant.

Charley Polachi is a partner at Polachi Access Executive Search with more than 30 years of experience recruiting top technology talent. “While these questions are popular at innovative firms, they are useful for college hires and not executives,” says Polachi. “Recruiters often use brainteaser questions for recent college graduates to understand their critical thinking process.”

How to answer brainteaser questions

When responding to a brainteaser question, the best general approach is to:

1. Take a moment to carefully consider the question. Don’t feel like you have to blurt out the first answer that comes to mind.

2. Ask any clarifying questions. Make sure you understand the question and what the interviewer is looking for. See if there is additional information available.

3. Walk through your thinking process out loud. Verbalize the steps you would take to solve the brainteaser and, if relevant, the data that you would need (making estimates and assumptions if necessary). Put the emphasis on your approach, not on the final answer.

Brainteaser Examples

Brain Cogs
1. The “How many?” Brainteaser

Here is a classic brainteaser beloved by interviewers:

“How many gas stations are there in the U.S.?”

Other variations include:
• “How many barbers are there in Chicago?”
• “How many piano tuners are there in New York?”
• “How many boxes of breakfast cereal are sold in the U.S. each year?”
• “How many golf balls will fit inside a Boeing 747?”

These questions (and the many other adaptations) ask the candidate to think through a problem.

Unless you are a walking encyclopedia, you will have to estimate some of the facts required to arrive at an answer.

For example, you will have to start with population numbers for the country or city, then draw conclusions from there about how many people in that number have cars or pianos or hair.

The interviewer does not usually expect you to arrive at the correct answer. She probably doesn’t know the correct answer herself. The idea is to hear how you think and see if you can analyze a problem and devise a way to solve it.

2. The Riddle Brainteaser

In a riddle brainteaser question, the interviewer will pose a bizarre situation and ask you what you would do. With these, the interviewer is looking for the ability to think on your feet and creativity in problem solving.

In the past, Google was known for asking tough riddle questions. Here’s a particularly challenging one that Google reportedly asked many candidates:

You are shrunk to the height of a nickel and thrown into a blender. Your mass is reduced so that your density is the same as usual. The blades start moving in 60 seconds. What do you do? Think about it and read on for the answer.

This is obviously a ridiculous question. There is no way that a candidate could have prepared for it (well, in the days before it was leaked all over the internet anyway). Asking it will give the interviewer some idea of how the interviewee can think on his feet and operate under pressure.

Then again, the ability to answer a question like this doesn’t usually translate to ability to perform on the job (even if the opening is for a blender designer).

Another famous riddle is, “How would you move Mount Fuji?” This question is commonly attributed to Microsoft (probably long retired, however). The idea with this one is that moving Mount Fuji is impossible. So what are your most creative ideas for tackling a seemingly impossible project?

Google, Microsoft, and many other firms have phased these riddle questions out. However, if you do get a question like this, try not to panic and just do your best to think through the situation out loud. Remember that these questions are meant to be tricky and the seemingly obvious answer is probably wrong.

Also, don’t let the riddle (or your struggle to answer it) throw you off and affect your confidence. This is just one question in the interview — and you can be sure that other candidates will struggle with it as well. Do your best, move on, and focus on wowing them with your answers to the other questions.

By the way, here are some acceptable answers to the blender question above (according to the book Are You Smart Enough to Work at Google? and various other sources):

a) You would just jump out of the blender. Supposedly, the physics of reducing your mass and maintaining your density would allow you to do that. No, I can’t explain the physics behind it. If you’re dying of curiosity, check out the book cited above.

b) You could lie down under the blades. You would be small enough to be safe there.

c) You could balance on the blade mechanism and go for a ride. This sounds much more unlikely to me. Then again, the whole scenario is preposterous, so you have to think creatively.

3. The Math Brainteaser

Some brainteasers are designed to test your math skills. These are often used in finance interviews.

They sometimes take the form of story problems (prepare for an SAT flashback). Another common math brainteaser involves presenting a series of numbers and asking what comes next and why.

Some focus on solving a problem by calculating probability. For example: “I roll two fair dice, what is the probability that the sum is 9?”

If you are starting out in a finance or technology career, you should be prepared to answer questions that test your math skills. You may want to practice solving some math brainteasers and work that muscle. For challenging math brainteaser examples (ranging from Difficult to Extremely Difficult), check out this site maintained by Stanford Ph.D. Haidong Wang.

4. Why Are Manhole Covers Round?

And finally, we have another well-known brainteaser question. It is said to have originated at Microsoft and has since spread far and wide.

It is so well known that most companies have stopped asking it. However, it can’t rightfully be left out of a post about brainteaser interview questions.

Why are manhole covers round?

The easiest and most common answer: Manhole covers are round so that they won’t fall into the manholes.

Some other answers:

• Because manholes are round
• Because they are easier to transport (just roll them)
• Because they are easier/cheaper to manufacture (smaller surface area than a square cover)

Preparing for Brainteaser Interview Questions

We are big believers in the power of interview preparation. If you are currently interviewing, it’s a good idea to be aware of brainteasers and how to approach them.

If you want to go a step further, you can research examples of brainteaser questions and answers online. Keep in mind that it will be difficult to predict EXACTLY which brainteaser questions you are likely to hear. However, it certainly can’t hurt to work out your critical thinking “muscles” a little bit.

Just don’t neglect the other critical components of your interview preparation (including practice) to stress about brainteaser questions.

VIDEO: While not technically a brain-teaser question, here’s a nice scene from “The Pursuit of Happyness” to inspire you:

MAIN PHOTO CREDIT: NinaMatthews

Written by

Pamela Skillings

Pamela Skillings is co-founder of Big Interview. As an interview coach, she has helped her clients land dream jobs at companies including Google, Microsoft, Goldman Sachs, and JP Morgan Chase. She also has more than 15 years of experience training and advising managers at organizations from American Express to the City of New York. She is an adjunct professor at New York University and an instructor at the American Management Association.

5 Comment to How to Answer Brainteaser Interview Questions

  • James F

    Great post! I’ve interviewed at google, and had some tough brain teasers given to me. The biggest thing for me, was not rushing to an answer. Its easy to get nervous and rush it.

  • Kyle

    Man hole covers are round because circles have a consistent diameter, so if you have a large object or tool that you need to get down, you don’t have to move it to fix exactly in a square’s largest spot (the corners), it will fit in any direction… just a guess… maybe i should interview at Microsoft 🙂

  • Jenn

    Those ‘how many’ questions are impossible! What could they learn from those?!?

  • Craig

    I hope I never get asked any of those math questions in an interview… I’d need a pen, paper, a calculator, and a math professor.

  • Lindsey

    Great post Pam! I, for one, am glad to see this stuff on its way out for big tech companies. I like to think theres more practical ways, and less stressful ways of determining someones abilities.