When is it OK to estimate? Is a fast estimate better than a slow but accurate answer?

Math is more than just a handy skill in consulting — it’s often a game-changer. Whether you're analyzing complex business challenges, building solid recommendations, or backing up your advice with hard data, strong math skills frequently set you apart in this field.Math in the Day-to-Day Life of a ConsultantMath is a cornerstone in daily life as a consultant. You’ll need to analyze complex issues, make quick estimations, and conduct precise calculations. Working with numbers and data is part of the job, and clients rely on you for recommendations that are both well-reasoned and reliable. Math becomes a crucial tool for making decisions and streamlining processes, helping you avoid getting lost in details or missing important insights.There are three key areas where math is indispensable in consulting:Problem-Solving EfficiencyConsulting often presents complex challenges. Math lets you approach problems systematically and efficiently, where even a rough estimate or quick calculation can reveal important insights early on. This can save time and avoid lengthy, unnecessary analyses.Math as a Trust BuilderYour math skills aren’t just about problem-solving — they’re also essential for building trust. Clients pay for expertise and expect solutions supported by rigorous analysis. When you can back up your arguments with clear numbers and accurate calculations, you strengthen your credibility.Estimation Skills: A Consultant's Must-HaveConsulting doesn’t always allow time for deep analyses. Often, you’re expected to make sound estimates quickly. Whether it’s sizing a market or estimating the cost of a business strategy, your ability to deliver prompt, well-founded answers is crucial. Strong estimation skills show you have a big-picture understanding and work efficiently.The Role of Math Skills in Case InterviewsMath skills are critical, even in the interview process for consulting roles. Case interviews test your ability to analyze business problems and perform quick calculations under pressure, with no tools like calculators or spreadsheets. Around 20-25% of the case interview assessment focuses on these “quant skills”, and in big consulting firms, like MBB and the big Four, they often make the difference between an offer and a rejection. Math abilities are more than a “nice-to-have”; they’re a core requirement for consulting success.Here are three things to keep in mind for your upcoming case interviews:Prepare for estimation questions: Questions like, “How many cars exist in Germany?” don’t need exact answers but rather a logical approach. This skill is crucial for market sizing cases, so it’s worth practicing.Be ready for mental math: While notes are allowed, simple calculations should be done mentally and quickly, demonstrating your flexibility with numbers.👉 Want to level up your math skills? Try out our mental math tool!Understand ‘hard’ and ‘soft’ errors: Calculation errors are “hard” mistakes because math demands accuracy — there’s no room for close-enough answers. “Soft” errors occur with less precise interpretations that, while not outright wrong, can lead to misunderstandings or inexact conclusions.Final ThoughtsMath skills are essential in consulting. They enable you to find accurate solutions, provide solid recommendations, and build client trust. Whether in a job interview or daily consulting work, confidence with numbers sets great consultants apart. By improving your math skills, you lay a solid foundation for a successful consulting career.Practice with these cases to sharpen your math abilities:👉 MBB Second Round - CodeWave Employee Turnover Challenge👉 Element Mobile Expands into Refurbished Phones👉 Telekom Strategy Consulting Case: Fiber Optic Expansion

Correlation and causality are two important terms in statistics that are often confused with each other. In this text, the difference between the two is explained with understandable examples and related to the business consulting industry. Keep in mind that math is an important aspect of the case interview.The Principle of CorrelationCorrelation describes the degree of relationship between two variables. When two variables correlate, it means that changes in one variable are accompanied by changes in the other variable. A positive correlation occurs when the values of both variables increase or decrease together. An example of a positive correlation is the relationship between the number of hours spent preparing for an exam and the score achieved. As a rule, the more time one invests, the better the exam score.A negative correlation occurs when the values behave in opposite ways, that is, when the value of one variable increases, the value of the other variable decreases, and vice versa. As an example, there may be a negative correlation between the number of hours one spends watching TV and physical fitness. The more time one spends in front of the TV, the less time one has for physical activities, which can lead to lower fitness.However, it is important to understand that correlation alone is not sufficient to conclude causality.The Principle of CausalityCausality means that a change in one variable is a direct cause of a change in another variable. In other words, one variable causes a change in another variable. An example often used to explain the difference between correlation and causality is the relationship between the number of ice cream sales and the number of sunburns. There is a positive correlation between these two variables because more ice cream is sold on sunny days and more people also get sunburned. However, it would be wrong to assume that ice cream consumption causes sunburns. In reality, the common cause of both is sun exposure. On sunny days, people buy more ice cream and are also at higher risk of sunburn. This example illustrates that correlation does not automatically indicate causation.Correlation and Causality in Management ConsultingIn consulting, understanding correlation and causality can play a critical role. When consultants analyze data to help companies or organizations, it is important that they draw the right conclusions and not make false assumptions. Usually it is important to decide which factors should be qualitative and/or quantitative analyzed.Let's say a company finds that there is a strong correlation between the use of a particular marketing strategy and sales growth. The company might be tempted to assume that the marketing strategy is directly responsible for sales growth and therefore continue to invest heavily in that strategy. However, it could be that the correlation only indicates that both variables are influenced by another, as yet unknown, cause. To confirm causality, further research would be required, such as experiments or bigger control groups to test the direct impact of marketing strategy on sales. Possible causes could also be pricing, a change in the product portfolio or the changing size of the market.Overall, it is important to understand that correlation and causality are different concepts. Correlation simply describes the relationship between two variables, while causality implies a cause-and-effect relationship. Just because two variables correlate does not automatically mean that one variable is the cause of the change in the other variable. Further investigation and evidence is needed to conclude causality.