Schedule mock interviews on the Meeting Board, join the latest community discussions in our Consulting Q&A and find like-minded Interview Partners to connect and practice with!
#1 Coach for Sessions (4.500+) | 1.500+ 5-Star Reviews | Proven Success: ➡ interviewoffers.com | Ex BCG | 10Y+ Coaching
Hi there,
Q: How do you mentally calculate 5*(1.25)^5 fast?
I believe you want to calculate an increase of 25% per year for 5 years.
The fastest approximation is probably with the rule of 72. Applying it, you get that you double in:
72/25 = 3 years
So after 3 years, you should be around 10.
Once you are there, you can either perform 10*1,25^2, or notice that you would double again in 3 years, so after that the result would be 20, as your new starting point is 10. Given you just have 2 iterations and not 3, the result should be somewhere between 15 and 16 (the actual result is indeed 15.3).
I think Ian and Francesco presented some good approaches here.
In general, with questions like this, the keys are going to be:
Rounding and simplifying
Breaking the calculation up into easier parts
But I don't think you'll be required to do a calculation like this with some compounding on the fly. Maybe as part of the quantitative portion, where you can write it out and take a moment to calculate it.
After +5 years of candidate coaching and university teaching, and after having seen hundreds of cases, I realized that the economic-related knowledge needed to master case interviews is not much, and not complex. However, you need to know where to focus! Hence, I created the guide that I wish I could have had, summarizing the most important economic and financial concepts needed to solve consulting cases, combining key concepts theorical reviews and a hands-on methodology with examples and ad-hoc practice cases.
It focuses on 4 core topics, divided in chapters (each of them ranked in scale of importance, to help you maximize your time in short preparations):
· Economic concepts: Profitability equation, Break even, Valuation methods (economic, market and asset), Payback period, NPV and IRR, + 3 practice cases to put it all together in a practical way.
· Financial concepts: Balance sheet, Income statement/P&L and Performance ratios (based on sales and based on investment), +1 practice case
· Market structure & pricing: Market types, Perfect competition markets (demand and supply), Willingness to pay, Pricing approaches, Market segmentation and Price elasticity of demand, +1 practice case
· Marketing and Customer Acquisition: Sales funnel, Key marketing metrics (CAC and CLV) and Churn, +1 practice case
Feel free to PM me for disccount codes for the guide, and I hope it helps you rock your interviews!
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.
20
9
Expert case by