Case Interview Prep Guide: MBB, Big 4 and Tech Strategy
A focused case interview prep guide — frameworks, math drills, PEI behavioural — for MBB (McKinsey, BCG, Bain), Big 4 and tech strategy roles.
Case interview prep is a math-and-structure exam dressed up as a conversation. Train both, separately.
What case interviews actually test
- Structure: can you decompose an ambiguous problem MECE in 60 seconds?
- Math: can you do mental arithmetic under pressure without errors?
- Communication: can you talk through your reasoning clearly and adapt to hints?
- Business sense: do your hypotheses sound like a consultant, not a student?
The 4 frameworks worth knowing
- Profitability tree: Profit = Revenue − Cost; split each into volume × price and fixed/variable.
- Market entry: market size + attractiveness + capability fit + go-to-market.
- M&A: strategic rationale, financials (synergies, valuation), execution risks.
- Customer / 4P: for product, pricing, positioning cases.
Math drills
10 min/day for 4 weeks: 2-digit multiplication, % change, breakeven, NPV basics, top-down sizing. Use scratch paper — interviewers expect it.
PEI / behavioural
4 PEI stories: entrepreneurial drive, personal impact, leadership, conflict. Each one needs a measurable result. See the STAR method guide — same structure works.
A 6-week prep plan
- Weeks 1–2: framework drilling, 10 market sizing problems, math reps.
- Weeks 3–4: 15 cases with partners (PrepLounge / RocketBlocks). Draft PEI stories.
- Weeks 5–6: 15 more cases, focus on weak case types. PEI dry-runs.
Generate practice cases on demand
Profitability, market sizing, M&A, PEI — pre-tuned for consulting.