Brain Teaser in Interview?

Bain BCG Case Interview McKinsey PEI
New answer on May 31, 2020
4 Answers
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Anonymous A asked on Dec 29, 2017

Dear prep lounge community,

In relation with brain teasers questions, which part of the interveiw does this type of questions usually come in? For companies like Mckinsey, BCG and Bain?

Will it be part of a FIT interview? or is there a dedicated session for it?

Thanks and regards,

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Chris replied on Dec 29, 2017
Feel free to reach out! Applying to MBB in 3-6 months. Others praise my the practice interview feedback I offer.

The brain teasers on this site are more like math problems or logic puzzles. You're not likely to encounter those in an interview.

More common in interviews (though not as much in case interviews) are brain teasers like, "how many golf balls can you fit into a passenger Boeing 747?" This question requires you to break down the problem area (the airplane's volume, which is made up of the cockpit, cargo hold, passenger area, etc.), make assumptions about it (the cockpit contains X cubic meters of space, the passenger area Y units, etc.) and do calculations (you can fit Z golf balls in X cubic meters, etc.). These questions test your ability to define a problem, break it down, and use math to solve it.

In case interviews, you more often see a business-oriented version of these, often called "estimation" or "back-of-the-envelope" questions. Though they often require similar techniques, estimation questions tend to focus on a market (e.g., the number of women's jeans sold per year or the vodka revenue in one night at a high-end night club) and are used to estimate the impact of a consultant's recommendation, often within a larger case.

For example, you may be completing a case with a clothing retailer and find that volume sales have declined significantly within a certain region where customers have turned to online shopping. You recommend the company invest in online retail platforms or form a partnership with an online retailer. Your interviewer sees your reasoning and asks you what the impact to the business's financials will be. You then have to estimate the revenue generated and compare that to the expected investment costs. Doing so allows you to take a recommendation ("partner with an online retailer") and actually calculate how much it helps you reach your client's goals.

As you prepare for your interview (and consulting itself), you can keep your skills sharp using the brain teasers on this site, but you'll want to really master estimation questions as they apply to business problem-solving and case interviews.

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Content Creator
replied on Dec 31, 2017
#1 Coach for Sessions (4.000+) | 1.500+ 5-Star Reviews | Proven Success (➡ | Ex BCG | 9Y+ Coaching

Hi Anonymous,

in my experience brainteasers are more typical in final rounds, in particular if you get a market sizing and you are quick to solve it. I agree with Vlad they are not frequent though – I got a couple of them in only one interview out of the 20+ I did when I applied for consulting (that happened in an MBB interview).



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Content Creator
replied on Dec 29, 2017
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School


There is no dedicated part of the interview for brainteasers and to be honest they are quite rare. Although the interviewer might want to ask you a brainteaser question either before or after the case.


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Content Creator
replied on May 31, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


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