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# Possessing general knowledge is indispensable especially for market sizing cases

In a case interview, you must be familiar with basic data about geographies, population, life expectancy, and economies especially for the country you are interviewing for and popular countries such as the US where most big consulting firms are based. Having this knowledge demonstrates that you are well-read and have the potential to be business savvy. Thus, besides being able to solve highly complicated algebraic problems, you should know basic information such as the population of your home country and some key countries of the world. Obviously, it would be embarrassing to not know the population of the country you live in especially if your client notices this!

Most importantly, you will likely need this information for most market sizing cases and backing assumptions with known facts such as population data makes the entire exercise of estimation much more plausible and reliable. Knowing such figures can also be beneficial for sanity checks at the end.

Here are some basic facts we pulled together for you (ideally you should memorize these or at least have an idea of the "order"  if not exact numbers):

 Population World total 7,8 b China 1,4 b India 1,3 b Europe 750m USA 330m Indonesia 270m Brasil 211m Russia 145m Japan 130m Germany 84m UK 68m

Last updated: 10/18/19

 Time Days/year 365 d Days / 3 years 1000 d Weeks/year 50 w Hours/week 168 h Seconds/hour 3600 s

Country/Region GDP (in trillion \$US)
World 85,804,391
1  United States 21.43
2  China 14.34
3  Japan 5.082
4  Germany 3.861
5  France 2.716
6   United Kingdom 2.829
7  India 2.869
8   Italy 2.004
9 Brazil 1.84

(Source: World Bank, last updated: 03/11/21)

 Fractions Percent Decimal 1/5 20% 0,200 1/6 17% 0,167 1/7 14% 0,143 1/8 13% 0,125 1/9 11% 0,111 1/10 10% 0,100 1/11 9% 0,091 1/12 8% 0,083 1/13 8% 0,077 1/14 7% 0,071 1/15 7% 0,067 1/16 6% 0,063 1/17 6% 0,059 1/18 6% 0,056 1/19 5% 0,053 1/20 5% 0,050

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### Article dates

Important Facts
Most recent answer on Oct 18, 2019
The best answer (on Oct 18, 2019) is from:
Christine
PrepLounge Community & Marketing Manager
Christine
gave the best answer on Oct 18, 2019
PrepLounge Community & Marketing Manager
Hi Radu, Thank you for your feedback and for helping us improve our practice material! We updated the data right away. If you have any more feedback or questions , feel free to contact us. Best, Christine PrepLou ... (read entire answer)
1
1.7 k
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on Oct 18, 2019 on Oct 18, 2019
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### # Wks per YEar

Important Facts
Most recent answer on Apr 25, 2021
The best answer (on Apr 25, 2021) is from:
Francesco
Expert
Content Creator
#1 Coach for Sessions (3.900+) | 1.400+ 5-Star Reviews | Proven Success (www.case.tools/results) | Ex BCG | 9Y+ Coaching
Francesco
Expert
Content Creator
gave the best answer on Apr 25, 2021
#1 Coach for Sessions (3.900+) | 1.400+ 5-Star Reviews | Proven Success (www.case.tools/results) | Ex BCG | 9Y+ Coaching
Hi there, Yes, in a year there are 52 weeks. However, you can usually ask the interviewer if you can simplify things and use 50, in particular if you are doing market sizing/estimation. It seems PrepLounge reported ... (read entire answer)
3
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on Apr 25, 2021 on Apr 25, 2021
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### EU has population of about 450m, how did count Europe with 750m?

Important Facts
Most recent answer on Jun 27, 2021
The best answer (on Jun 18, 2021) is from:
Ian
Expert
Content Creator
BCG | 100% personal interview success rate (8/8) and 95% candidate success rate | Personalized interview prep
Ian
Expert
Content Creator
gave the best answer on Jun 18, 2021
BCG | 100% personal interview success rate (8/8) and 95% candidate success rate | Personalized interview prep
Hi Nina, It's absolutely critical that you improve your knowledge of the world (geography, world events, etc.). The EU is not Europe. The EU is a group of European countries (27 to be exact). Europe has many more.  ... (read entire answer)
2
642
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21
on Jun 27, 2021 on Jun 27, 2021
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Interview First Aid
Starter's Guide to Case Prep
Crack the Case Interview
Ace the Personal Fit Interview
Master the Problem Solving Test
Case Cracking
Identify your Case Type