Numbers to know for interview

Actively preparing for interviews at McKinsey and BCG benchmarking numbers
New answer on Mar 31, 2022
6 Answers
Anonymous A asked on Mar 26, 2022

Hello all :)

next to obvious numbers like e.g. # of households or life expectancy, I was wondering which other numbers would be good to know for the interviews (e.g. per capita income).

Many thanks in advance!

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replied on Mar 27, 2022
BCG 1st & Final Round interviewer | Personalized prep with >95% success rate | 7yrs coaching | #1 for Experienced Hires

Hi there, 

I'm with Ankit on this one - it is definitely NOT A MUST to memorize such stats and numbers. A case interview is not an exam that tests memorization skills. 

That said, when a candidate comes across as generally knowledgeable, well-read about a market / general macroeconomic conditions in a given markets, it can definitely leave a strong impression and score plus points - typically lends a candidate a credibility & a more mature, experienced appearance. Also, it makes you life easier to come up with well-reasoned and fact-based assumptions in a case interview + increases efficiency - which is a critical factor to pass.

Having said that, if you are willing to put to go the extra mile, here are a few types of stats that can become very handy for all kinds of market sizings, profitability type questions,  “free-flow” bigger picture conversations with a partner etc

  • Economic: GDP per capita & growth, avg. individual & household incomes, CPI, income & corp tax rates 
  • Demographic: total population (e.g country & largest metro areas), avg. household size, life expectancy, avg. age & age distribution (esp for emerging markets → very distinct)
  • Other (select): # of tourists / visitors per year, urbanization rate, % smart phone penetration, literacy rate

It's never a bad idea to develop a good feel for such numbers, at least for the local market where you're interviewing + maybe select globally-leading markets (e.g. US, EU, China). But again, no point in memorizing just for the sake of it.

I have a cheat sheet that captures stats for different key markets - do reach out via PM, if interested and/or if you'd like learn more on how to best use such data points to maximize case performance.

Hope this helps.

Regards, Andi 


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Anonymous replied on Mar 27, 2022

hi there, 

Frankly, i don't think you need to memorize any numbers really before going into an interview esp. GDP etc. You need to have a logical sense of some broad macro numbers such as population, typical income band split etc. (esp. for the country of office which you are interviewing for). You should always be prepared for curveball questions where you would have no clue about the numbers you are required for market sizing. In such cases, try to make some assumptions based on logical reasoning and be transparent with the interviewer that you are not sure about some numbers. Interviewers will appreciate that and will help you as needed.

Good luck!


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Content Creator
replied on Mar 27, 2022
MBB | 100% personal interview success rate (8/8) and 95% candidate success rate | Personalized interview prep

Hi there,

Sounds like you're asking for market sizing. I have a full sheet of all the numbers you need to know, so feel free to reach out!

Just off of the top of my head:

  • Average income
  • Income bands
  • Average age
  • Age bands
  • GDP
  • GDP of Key industries
  • Key country population and GDP numbers
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Content Creator
replied on Mar 31, 2022
Highest-rated McKinsey coach (ratings, offers, sessions) | 450+ offers | Author of The 1% & Consulting Career Secrets

Hi there,

No need to memorize any numbers.

For market sizing questions it helps to know 

  • population numbers for your region
  • average household size
  • rough GDP / capita estimates



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replied on Mar 28, 2022
Bain | EY-Parthenon | Roland Berger |Former Head Recruiter | Market Sizing

You should read CIA Factbook on the target country as it will have the key statistics and description of economic activity and demographics in they country.

You don't need to know everything by heart. But a consultant is expected to have a good level of curiosity about the world - which means that knowing some key facts is expected. It makes the difference between being perceived as an immature inexperienced candidate, and a candidate that is ready to hit the ground running and can be put in front of a client.

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Content Creator
replied on Mar 27, 2022
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


Overall, you don´t need to know any of these by heart (none will judge you for not knowing the population of country x, of the average family size in country y). However, your intuition is correct: if you have worked with these numbers before, you can give a better estimation, which is always good. 

I would just have a look at the biggest countries rough population, since average family size in those can be easily guessed and double checked with the interviewer. 

Hope it helps!



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Andi gave the best answer


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