In case interviews, having solid general knowledge can make a big difference, especially in market sizing questions. Knowing basic facts about regions, population sizes, and economic indicators helps you build stronger arguments. It’s not just about the analysis itself but also about showing interviewers that you understand global trends and can quickly process key information — an important skill in consulting.
In a case interview, quick and accurate estimates are essential. For example, if you're asked to evaluate the potential market for a product in a specific country, having solid data — like the population size — is crucial. Without this information, it can be challenging to make a meaningful calculation.
In addition to national market data, it's important to know about key global markets. Being familiar with major economic regions like the U.S., China, and the EU is valuable because large consulting firms such as McKinsey and BCG operate extensively in these areas. A solid understanding of these regions shows that you can think about global factors and helps you stand out from other candidates.
What Your Knowledge of Population, Economy & Geography Says About You
Having strong general knowledge in specific areas not only shows that you are well-prepared, but also that you can quickly understand economic relationships—a crucial skill in consulting. When you have information like population sizes or a country's Gross Domestic Product (GDP) at your fingertips, you can quickly verify assumptions and make informed decisions, which is exactly what case interviews expect.
Additionally, your knowledge of these topics demonstrates a genuine interest in world affairs and your ability to recognize and understand global trends. This insight is vital for evaluating how political, economic, and social changes affect businesses. It also highlights your capability to absorb and use complex data effectively.
Population
Country/Region
Population (approx.)
Worldwide
8.05 billion
China
1.426 billion
India
1.419 billion
Europe (EU states)
450 million
USA
335 million
Indonesia
277 million
Brazil
203 million
Russia
143 million
Japan
124 million
Germany
83 million
UK
68 million
GDP Forecast in USD for 2024
Country/Region
GDP 2024 (approx. in trillions USD)
Worldwide
105 trillion USD
USA
25 trillion USD
China
18 trillion USD
Japan
4.3 trillion USD
Germany
4.5 trillion USD
France
3.0 trillion USD
UK
3.1 trillion USD
India
3.9 trillion USD
Italy
2.2 trillion USD
Brazil
2.1 trillion USD
Canada
2.2 trillion USD
Key Data to Know for Your Case Interview
In case interviews, making quick and accurate estimates is key. A good grasp of units, along with basic fraction and percentage calculations, is essential for working efficiently. Additionally, being comfortable with time units is important for making rough estimates and calculations. The table of larger and smaller time units below provides a handy overview of commonly needed values. These fundamental skills help you tackle tasks confidently and quickly.
Overview of Time Conversions: Days, Weeks and Hours
Larger Units
Smaller Units
Days/Year
365 days (In leap years: 366 days)
Days/3 Years
1,095 days
Days/4 Years
1,461 days (including 1 leap year)
Weeks/Year
52 weeks
Hours/Week
168 hours
Seconds/Hour
3,600 seconds
Conversion of Fractions to Percentages and Decimal Values
Fraction
Percentage
Decimal
1/5
20%
0.20
1/6
16.67%
0.1667
1/7
14.29%
0.1429
1/8
12.5%
0.125
1/9
11.11%
0.1111
1/10
10%
0.10
1/11
9.09%
0.0909
1/12
8.33%
0.0833
1/13
7.69%
0.0769
1/14
7.14%
0.0714
1/15
6.67%
0.0667
1/16
6.25%
0.0625
1/17
5.88%
0.0588
1/18
5.56%
0.0556
1/19
5.26%
0.0526
1/20
5%
0.05
Remember, it’s not enough to just memorize these numbers—you also need to be able to calculate with them effectively!
Use our Mental Math Tool to specifically train your math skills and prepare for your next interview.
Let's Move On With the Next Articles:
Preparation Plan
Consulting Skills & Preparation
Preparing for a case interview can feel overwhelming, but having a structured plan will help you stay focused and make steady progress. A well-organized approach ensures you build a strong foundation, practice effectively, and refine your skills before the big day.In this guide, we will walk you through the key components of an effective practice plan, including self-study, peer practice, and working with a coach. Let’s go!
In every preparation plan, you take center stage. 🎯 And with you, one of the most important components in preparing for your case interviews: the self-study part. In the realm of self-study, you have various opportunities to familiarize yourself with the fundamental concepts and frameworks. This involves grasping the theoretical foundations and then applying them to practical cases.It is less important to memorize everything. Instead, you should try to analyze the cases independently and use the frameworks as a basis to develop your own customized structures.Self-study is essential because it lays the foundation for a deep understanding of problem-solving and fosters the ability to solve problems independently and creatively. By independently working through and applying the concepts, the knowledge is firmly anchored, which is particularly beneficial in practice.
Preparing for case interviews is a crucial step for success in the consulting industry. These interviews are known for their complexity and the high demands they place on applicants. One of the most effective methods for preparing for case interviews is practicing with like-minded peers. PrepLounge offers excellent opportunities to find suitable interview partners for joint practice with the world's largest case interview community. This article highlights why practicing with like-minded peers is beneficial, how to optimally use PrepLounge's resources, and provides tips on how to get the most out of mock interviews.
