A consulting case interview asks you to work through a problem with another person. Preparation should make your thinking clearer and more flexible, rather than give you a script that only works when the question is familiar.

We compared four CareerFairy Live Streams: BCG's case-preparation session, Roland Berger's application training, BCG Platinion's entry conversation and its hackathon spotlight. The hackathon is a different setting from an interview, but its discussion of business goals, technical decisions and communicating a solution adds useful context about technology consulting. Watch the recordings: BCG (2025-11-19), Roland Berger (2025-10-13), BCG Platinion (2026-04-27), BCG Platinion (2026-09-07).

The quick answer: Clarify the client's objective, build a structure that fits the problem, explain your assumptions and work through evidence openly. Practise with a partner and review specific weaknesses. Learn frameworks as starting points, but adapt them. Prepare personal fit too, and follow the instructions for the firm and office interviewing you.

These conversations took place between October 2025 and September 2026. The interview and event details belong to those dates. Current invitations and recruiter guidance should determine your preparation plan.

What are consulting firms actually assessing in a case?

They want to understand how you approach and explain an unfamiliar problem.

BCG described the case as a conversational problem-solving exercise: the interviewer sets a scene and provides a problem, then the candidate works through it with them. It involves both qualitative reasoning and calculations as the problem becomes more specific.

Roland Berger's interviewers described a broader set of dimensions, including structure, analytical thinking, creativity, commercial understanding, communication and presentation. They emphasised the method and reasoning rather than only the final result.

BCG Platinion's entry speaker likewise highlighted understanding the case and responding to comments or questions. The ability to react matters because consulting work with clients also brings unexpected information and requests.

That suggests a useful change in how you judge practice. Do not ask only whether you obtained the answer in the sample solution. Ask whether another person could follow your reasoning, whether your assumptions were sensible and whether your recommendation addressed the original problem.

What should you do when the interviewer gives you the problem?

Establish what the client wants to achieve before choosing an analysis.

BCG demonstrated this with an ultra-luxury car manufacturer's question about bringing outsourced call centres in-house. The first step was to clarify the rationale and exact objective. Was the client seeking lower costs? Was there a target level of savings? Those answers shape what you need to compare.

A structure that is appropriate for cost savings might be insufficient if the main concern is service quality. The case is not just a calculation with a business story attached. The objective tells you which evidence matters.

Our practical way to apply this advice is to restate the question and confirm the decision the client needs to make. Then identify the main dimensions you would investigate. Explain why those dimensions could change the answer.

This is a preparation habit, rather than a fixed opening that every interviewer expects word for word. The aim is shared understanding of the problem before you start solving it.

Should you memorise consulting frameworks?

Learn what they help you notice, but do not force them onto every case.

Roland Berger's session contained both sides of that advice. The speakers recommended becoming familiar with common frameworks because they can help you retain structure. They also warned that frameworks need adapting to context and that some cases cannot be solved by applying a standard one.

One interviewer explicitly encouraged candidates to keep using ordinary reasoning and identifying the actual problem. A framework is useful when it helps you ask relevant questions. It becomes a problem when it distracts from the situation in front of you.

BCG also described preparation as individual. Some applicants gained confidence by doing more cases; others risked becoming over-structured or expecting a framework for everything. BCG Platinion similarly said memorising every case was less useful than developing an understanding and responding well.

When practising, explain why each branch of your structure belongs there. If you cannot connect it to the client's decision, reconsider it. The test is relevance, not how closely your notes resemble a page in a preparation book.

How do you make assumptions without just guessing?

State them, explain their logic and keep them plausible.

Roland Berger discussed market estimates and assumption-based calculations. Its interviewers wanted to see how the assumptions were built and whether they reflected reasonable commercial understanding. The final number was less informative without the logic behind it.

In its example of a client in crisis, the session moved from possible causes and strategic responses to new products and an estimate of their annual revenue. Each stage required a different kind of thinking. The revenue estimate then needed assumptions that another person could inspect.

BCG's call-centre example likewise involved information a candidate would not know from memory, such as operating cost per minute. The speaker described using provided data or reasonable estimates, then examining whether the conclusion made sense.

In practice, separate a fact given by the interviewer from an assumption you introduce. Say which variable you are estimating and why. If the result depends heavily on it, discuss what a different value might change. This makes uncertainty visible without preventing you from progressing.

How much maths do you need for a case interview?

You need to handle the calculation required by the problem and explain what it means.

BCG said cases combine qualitative thinking with numerical work, such as estimating savings or impact once the question becomes more concrete. Roland Berger also valued largely accurate calculation, while explaining that every result did not need to be perfect to the final decimal place.

The practical implication is to practise enough that basic arithmetic does not consume all your attention. At the same time, a mathematically correct number is not the end of the analysis. Connect it to the business decision.

In BCG's example, the comparison between in-house and outsourced costs supported a recommendation. The speaker also suggested challenging the result and considering benchmarks. A calculation that points one way may still rest on an assumption worth testing.

During practice, ask your partner to check both the method and interpretation. Can they understand what you are multiplying or comparing? Does the outcome support the recommendation you give? Those questions are more useful than treating speed as the only goal.

What should you do if you make a mistake?

Acknowledge it and correct the reasoning instead of trying to hide it.

BCG's November 2025 speaker gave this advice directly. If you notice that you have made a mistake, say so rather than covering it up. The interview is a conversation, and explaining a correction helps the other person follow what changed.

Roland Berger similarly encouraged authentic responses and remaining composed when interviewers ask follow-up questions. Candidates do not need a perfect response ready for everything.

Our synthesis is to identify the specific error, explain the corrected approach and update the conclusion if necessary. Avoid a long apology that stops the problem-solving conversation. Equally, do not continue defending a result once you see why it is wrong.

Use practice to make this less alarming. Ask your partner to challenge an assumption or calculation. Working through that moment is part of preparation, not proof that the exercise went badly.

How should you finish a case?

Give a recommendation connected to the objective you clarified at the beginning.

BCG's call-centre demonstration returned to the client's original question after comparing the costs. The recommendation summarised the analysis and explained why the company should or should not bring the activity in-house under the assumptions discussed.

That is more useful than listing every number you calculated. The interviewer should hear the decision, the main reasons and the important limits of the evidence.

For practice, try ending with a concise recommendation and then explaining the two or three findings that support it. Mention a material uncertainty or further check where it could affect the decision. This is our suggested exercise based on the session, rather than a prescribed closing formula.

If you have not resolved every aspect, be clear about what you can conclude from the information available. An honest conditional recommendation is easier to assess than an unsupported declaration of certainty.

How many practice cases are enough?

The speakers gave personal examples, rather than a universal quota.

In BCG's November session, one participant described doing around twenty cases over several weeks, while another recalled roughly twenty to thirty. They both connected preparation to feeling comfortable with the exercise. The first speaker explicitly said the right amount depended on the person.

The lesson is therefore not to stop at a particular count or assume that a larger number guarantees success. Review whether you can handle unfamiliar questions, explain a structure and respond to feedback.

BCG recommended learning the basic format, watching or reading examples and then practising realistic settings with another person early. University contacts and preparation communities could help students find partners. BCG Platinion also encouraged practice and described example cases available through its preparation resources.

Choose a manageable rhythm and record what you need to improve after each exercise. If you repeatedly struggle with assumptions, practise that part deliberately before adding more complete cases. If your reasoning is clear but your recommendation is hard to follow, work on the conclusion.

How is a technology consulting case different from a hackathon?

A hackathon involves building and presenting a team solution; a case interview is a selection conversation. Do not treat one as the other's exact format.

BCG Platinion's September 2026 hackathon session emphasised agreeing a shared goal, building something functional quickly, getting feedback and improving it before the final presentation. The speakers also said the jury would ask about technical choices, rather than being satisfied with only an interface.

Its consulting-entry session described problems that went beyond the technology itself, including organisational structures, incentives and programme management. Together, those accounts show why a technical answer needs a business context and an explanation of implementation.

The transferable preparation point is to connect a proposed solution to the problem it solves. Explain how it works, what constraints matter and why you chose it. The hackathon's specific tools, team format and event arrangements should not be assumed to apply in a recruitment interview.

Why should personal-fit preparation stay in your plan?

Because a strong case performance is only one part of the conversation.

BCG discussed motivation, experiences and future wishes alongside problem-solving. Roland Berger's interviewers said candidates sometimes neglected the personality interview even though it gave them space to explain who they were and learn about the firm.

Prepare a clear reason for wanting the work and examples of how you collaborate, take responsibility and learn. Keep them grounded in your own experience. The same clarity you use in a case can help someone understand a university project or an internship contribution.

Also prepare questions about the employer. The interview is a chance to decide whether the work and people fit you. Technical and personal preparation support each other when both help you communicate naturally.

Frequently asked questions about case-interview preparation

Do I need to know every industry in advance?

BCG did not expect candidates to know every industry by heart. Its speakers encouraged general awareness and business thinking while approaching the actual problem openly.

Are frameworks useless?

No. Roland Berger said they can help with structure, but need adapting. Use them to support reasoning rather than replace it.

Is the final number the most important part?

Roland Berger emphasised structure and assumptions as well as accurate arithmetic. BCG connected calculations to the client's decision and recommendation.

Should I practise alone or with someone?

Individual study helps you learn the format. BCG also recommended realistic practice with a partner so you experience explaining and responding in a conversation.

Does doing thirty cases guarantee that I am ready?

No. The figures in the BCG session were personal experiences, not a guarantee or required quota. Judge progress by the skills you can demonstrate.

Will my interview follow the same process as these sessions?

Not necessarily. Firm, office and entry route can affect the format. Use the current invitation and recruiter-provided material to guide preparation.

Explore upcoming CareerFairy Live Streams to hear from consultants and ask about their work and selection process.

Live Streams behind this guide

This article draws on the following CareerFairy recordings. Programme details and recruitment processes reflect the dates of the conversations.

• BCG: Consulting@BCG: How to Prepare For a Case Study (2025-11-19)
• Roland Berger: Fit für deine Bewerbung – Lerne Roland Berger kennen und erhalte wertvolle Tipps für deinen Bewerbungsprozess in der Strategieberatung! (2025-10-13)
• BCG Platinion: Tech trifft Strategie: Dein Einstieg bei BCG Platinion (2026-04-27)
• BCG Platinion: Event Spotlight: Was dich beim BCG Platinion Hackathon erwartet (2026-09-07)

Want to ask employers your own questions? Explore upcoming CareerFairy Live Streams to hear directly from recruiters and employees.