How to divide and multiple thousands, milions and bilions fast?

When preparing for a case interview in consulting, you will quickly realize that math is an essential component. Don’t worry, you don’t need to be a math genius – it’s enough to handle numbers in a structured and confident manner. Important Calculations and Computations in Case InterviewsLet's take a look at the types of calculations required and how you can best prepare for them. Typically, math in case interviews is usually tested in the following ways: 1. Basic Arithmetic OperationsThe foundation of any mathematical task is basic arithmetic: addition, subtraction, multiplication, and division. Quick and error-free calculation, either mentally or on paper, is crucial.2. Percentages and FractionsPercentage calculations and working with fractions are often part of case interviews. You should be confident in calculating percentages and converting fractions to decimals and vice versa. This is especially relevant for tasks such as capacity change or profitability analysis.3. Estimation QuestionsEstimation questions test your sense of magnitude and your ability to quickly provide plausible numbers. Practice making rough estimates for various scenarios, such as the size of a market or the number of customers in a store.4. Charts, Data, and TablesIn many interviews, you will be presented with data in the form of charts and tables. Your task is to quickly analyze this data and draw the correct conclusions. Practice recognizing data patterns and filtering out relevant information. Here, you can practice with Numerical Reasoning Drills!5. Word ProblemsWord problems test your ability to understand and solve mathematical problems from a written scenario. It’s important to handle these types of tasks confidently and quickly. In our Brainteaser Library, you will find many word problems that require mathematical skills. Solve them now!

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:1. 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.2. Be ready for mental math: While notes are allowed, simple calculations should be done mentally and quickly, demonstrating your flexibility with numbers.