Decode a Case 🔍
Describe a business problem — get the right framework, approach, and solution steps explained simply.
The photo is typed out for you on your own device - it is not uploaded anywhere. Works best on clear printed text; handwriting is not reliable.
How this works
This is a rule-based study guide, not a live AI model. It matches your problem to one of 7 common case types (profitability, market entry, M&A, pricing, growth, market sizing, operations) using keywords, then recommends the framework chain and step-by-step approach from standard consulting methodology — the same structures McKinsey, BCG, and Bain teach (hypothesis-driven thinking, MECE, issue trees). It adapts advice for your chosen geography, because regulation, market norms, and common pitfalls differ between India, the US, and the UK.
Interview formats: McKinsey interviews are typically interviewer-led (they guide the structure), while BCG and Bain are typically candidate-led (you drive the framework) — though formats often vary by role and office. This tool trains you for both.
The Framework Vault 💼
frameworks used in real consulting — from must-know core to rare situational tools. Each one shows when to use it, the steps, and where it comes from. 30 include a clickable link to the original source; the rest cite the original book or paper (more links coming).
See it solve a case: the BCG matrix in action 🧭
A fictional example, written to teach the method: a beverage company sells three products. Where should the next rupee of investment go?
ColaX - the market leader in a cola market growing 2% a year. EnergyUp - an energy drink in a market growing 18% a year, but the brand's share is a quarter of the leader's. FizzPop - a fizzy-candy soda in a market growing 1%, with a tenth of the leader's share; it still earns Rs 8 crore a year with no investment.
How a consultant works it: (1) Plot each unit on the two axes - that is analysis, not the answer. (2) Fund Stars from Cash Cows: ColaX throws off cash, EnergyUp needs it. (3) Question Marks get a decision, not a label: can EnergyUp realistically take share (distribution, brand spend, taste tests)? If yes, invest toward Star; if no, sell or shrink before it eats the cow. (4) Dogs do NOT mean automatic exit - FizzPop earns Rs 8 crore with zero investment, so harvest it quietly while it pays for itself. The matrix allocates attention; the exit-or-invest call still needs market, capability and cash-flow checks.
The Case Closet 👗
Caseflix 🍿
Full-length video lessons from real YouTube creators, lined up in the order I'd watch them: first understand the interview, then frameworks, then the math, then watch real mock interviews. Tap any thumbnail to load and play it right here from YouTube - we don't host or re-upload anything, and all credit goes to the creators.
1 · Start: what even is a case interview? 🌱
Watch one of these first. No prep needed, just press play.
2 · Frameworks, without the panic 🧩
How to actually use them instead of memorising names. Pair this with The Vault 💼 tab.
3 · Case math that doesn't scare you 🔢
Market sizing and guesstimates, explained slowly. The third one is by an Indian creator.
4 · Guesstimates, step by step 🧮
"Guess how many..." questions, taught slowly with real examples. Pair this with the Guesstimate Gym 🧮 tab - watch one, then try the practice questions there.
5 · Watch real mock interviews 🎤
Full interviews with real interviewers. Notice how they think out loud, then steal their structure.
Binge lists 📺
Whole playlists from established prep channels, one per topic. These open on YouTube - still free, still their content.
Guesstimate Gym 🧮
"How many chai cups does Mumbai drink a day?" Learn to crack market-sizing questions with decomposition, honest assumptions and sanity checks - then practice.
The 5-step method (works on any guesstimate)
- Clarify the question. Per day or per year? One city or all of India? Cups sold or cups consumed? Half the mistakes are answering a different question than the one asked.
- Decompose into a multiplication. Break the big number into 2-4 factors you CAN estimate (population x share x frequency). If a factor feels like a wild guess, break it down one more level.
- State every assumption out loud. Say "I am assuming" before each number. An interviewer can challenge an assumption; they can't challenge a number you pulled from nowhere.
- Do the math in round numbers. 2 crore x 25% x 1.5, not 19,983,442 x 0.247. Fake precision is a red flag, not a flex.
- Sanity check against something you know. Compare with a second path (bottom-up vs top-down) or a real-world anchor. If the two paths disagree by 10x, find the broken assumption.
Worked example 1: How many cups of chai are sold in Mumbai every day? ☕
Step 1 - Clarify: cups SOLD (not made at home), per day, Mumbai metro area.
Step 2 - Decompose: cups = population x share who buy chai outside home on a given day x cups per buyer.
Step 3 - Assumptions: Mumbai metro population: about 2 crore. Share buying chai outside home daily: about 1 in 4 (office-goers, students, commuters - chai is everywhere, but not everyone buys daily) = 50 lakh buyers. Cups per buyer: about 1.5 (one with breakfast, maybe one at 4pm).
Step 4 - Math: 2 crore x 0.25 x 1.5 = 75 lakh cups a day.
Step 5 - Sanity check: a roadside stall sells roughly 200 cups a day, so 75 lakh cups need about 37,500 stalls - roughly one stall per 500 residents. For a city where every station, office gate and corner has a stall, that feels right. Final answer: about 75 lakh cups a day, defensible range 50 lakh to 1.5 crore.
Worked example 2: How many smartphones are sold in India every year? 📱
Step 1 - Clarify: new phone sales (not second-hand), per year, all of India.
Step 2 - Decompose: sales = existing users replacing phones + first-time buyers.
Step 3 - Assumptions: India has about 140 crore people; assume about 45% use a smartphone = about 63 crore users. Average replacement cycle: about 3 years (budget phones age fast, premium slower). First-time buyers: small now, assume about 1-2 crore a year.
Step 4 - Math: 63 crore / 3 = about 21 crore replacements, plus 1-2 crore first-time = about 22 crore phones a year.
Step 5 - Sanity check: 22 crore phones at an average street price of about Rs 15,000 implies about Rs 3.3 lakh crore of phone spending a year - big, but consistent with electronics being one of India's largest consumer categories. Final answer: about 20-22 crore phones a year; anywhere in the 15-25 crore range is defensible with clean assumptions. If your math lands on 2 crore or 2 billion, an assumption is off by 10x - go find it.
Practice: 8 questions, easy to stretch 🏋️
Try each before opening its worked path. Warm-up first, stretch last - same 5 steps every time.
Warm-up: How many cups of chai does your own hostel or PG drink in a day?
- Clarify: chai made or bought for residents, per day, one building.
- Assumptions: 200 residents; about 70% drink chai; about 1.5 cups each per day.
- Math: 200 x 0.7 x 1.5 = 210 cups a day.
- Sanity: one shared kitchen kettle run twice for 100+ people tracks. Range: 150-300. Small scale, big confidence - this is the method working at its friendliest size.
Q1: How many cups of tea/coffee does one big office district serve per day?
- Clarify: bought cups, per working day, one large business district.
- Assumptions: about 50,000 office workers in the district; about 60% buy at least one cup; average 1.2 cups per buyer.
- Math: 50,000 x 0.6 x 1.2 = 36,000 cups a day.
- Sanity: 36,000 cups across about 60 outlets = 600 cups per outlet per day - busy but believable for a boom district. Range: 25,000-50,000.
Q2: How many flights take off from Delhi airport per day?
- Clarify: departures only, per day, all terminals.
- Assumptions: about 7 crore passengers pass through per year; roughly half are departing = 3.5 crore; average departure carries about 160 passengers.
- Math: 3.5 crore / 365 = about 96,000 departing passengers a day; 96,000 / 160 = about 600 departures a day.
- Sanity: 600 departures across about 17 operating hours = about 35 takeoffs an hour, or one every ~2 minutes across 3 runways - plausible for a busy hub. Range: 500-800.
Q3: Estimate the daily revenue of one city multiplex.
- Clarify: tickets + food, per day, one multiplex (not the chain).
- Assumptions: 10 screens x 250 seats x 4 shows a day = 10,000 seats on sale; occupancy about 40%; average ticket about Rs 280; food and drinks add about 40% on top of tickets.
- Math: 10,000 x 0.4 = 4,000 tickets; 4,000 x Rs 280 = Rs 11.2 lakh in tickets; plus 40% food = about Rs 15-16 lakh a day.
- Sanity: weekdays quieter, weekends packed - the 40% average hides the swing, so give a range. Range: Rs 8-20 lakh a day.
Q4: How many deliveries does one food-delivery rider finish in a day?
- Clarify: completed drops, per rider, per working day.
- Assumptions: about 10 working hours; a drop takes about 20 minutes door to door (wait + ride + handover), so about 3 an hour.
- Math: 3 x 10 = 30 deliveries a day.
- Sanity: about 750-900 a month; at typical per-order payouts that lands in the same order of magnitude as commonly reported rider earnings. Range: 20-40.
Stretch 1: Estimate the yearly revenue of India's wedding photography market.
- Clarify: money paid to photographers for weddings, per year, all India.
- Assumptions: about 1 crore weddings a year (a commonly cited ballpark - say it as an assumption, not a fact); about 30% hire a professional photographer; average spend about Rs 50,000.
- Math: 1 crore x 0.3 = 30 lakh shoots; 30 lakh x Rs 50,000 = about Rs 15,000 crore a year.
- Sanity: that is roughly 0.1% of household spending - plausible for a country that treats weddings as its biggest family expense. Range: Rs 5,000-25,000 crore, driven mostly by the 30% and the Rs 50k assumptions. Say which assumption you would defend longest.
Stretch 2: How many litres of petrol does one busy city fuel station sell in a day?
- Clarify: litres dispensed, per day, one busy urban pump.
- Assumptions: about 800 vehicles a day (one every ~90 seconds across 16 open hours); average fill about 8 litres (bikes less, cars more).
- Math: 800 x 8 = about 6,400 litres a day.
- Sanity: at about Rs 105 a litre that is roughly Rs 6.7 lakh of sales a day, about Rs 24 crore a year - believable for a busy pump, low for a highway one. Range: 4,000-12,000 litres.
Stretch 3: How many parcels does one mid-size courier hub sort in a day?
- Clarify: parcels passing through sorting, per day, one city hub (not the whole company).
- Assumptions: the hub feeds about 50 delivery routes; a rider finishes about 80 parcels a day; outbound sorting matches delivery volume; inbound/returns add about the same again.
- Math: 50 x 80 = 4,000 outbound; about 8,000 parcels sorted a day in total.
- Sanity: 8,000 parcels over a 10-hour sorting window is about 13 a minute on one belt with a small team - busy but physical. Range: 5,000-15,000.
Guesstimate rules to live by 📏
- Every number is either given or an assumption - label which, every time.
- Round early, round often. The structure earns the marks, not the third digit.
- Finish with a range and a sanity check, never a single magical point estimate.
- If two independent paths disagree, revisit the biggest assumptions first. How close is close enough depends on the question - state your range and what would change it.
- Practice under time pressure in Guesstimate Rush 🎯 in Case Arcade - same skill, game speed.
Daily Case Drop 🎭
One character. One mess. Tough calls - every single day. New quiz drops at 6 AM IST; the full answer sheet and video unlock at midnight IST.
Daily Case Drop 🎭
A new character walks in every day with a new mess. Lock in your answers, no peeking. Full answer sheet + video unlock at midnight IST. New quiz 6 AM IST. 🌅
Past Drops 📼
Every past quiz stays here. Answer sheets and videos unlock at midnight IST after each quiz day. Your picks are saved only on this device, separately for each day.
Case Arcade 🎮
Short games that teach case skills while you play, with instant feedback. The daily quiz lives in its own tab: Daily Drop 🎭.
Framework Match 🧩
Read the case prompt, pick the framework you would open with. Six rounds.
Guesstimate Rush 🎯
Estimate the number. Close counts - after each round you get one clean worked solution. Five rounds.
Study Stash 🔗
Every link below was opened and checked. PDFs download directly; firm pages contain the practice case and its official suggested answers.
My Wins 🏆
Cases you have opened, solutions you have checked, and analyzer runs. Saved to your account in the cloud, visible only to you. Highlights/underlines in the reader stay on this device.
Log in to save your progress
Create a free account with just an email and password. Your history is stored in your own private space and is visible only to you.
New Here? Pull Up 🎀
No prior knowledge needed. This path explains what a case interview is, walks you through one simple solved example, and shows you exactly what to do next.
What is a case interview?
Consulting firms (and many B-schools) test you with a business problem instead of quiz questions. The interviewer describes a situation - "a company's profits are falling" or "should we launch in a new city?" - and you think through it out loud. There is no single right answer. They are watching how you structure your thinking, whether you ask good questions, and whether your recommendation follows from your analysis.
Read the solved example below
See how a real case answer is structured - in plain language, no jargon.
Try one yourself
Open the Case Library, pick any original case, attempt it, then check the worked solution.
Analyze your own problem
Got a case from class or an interview? Type or photograph it in the Case Analyzer for a suggested approach.
A simple solved example
The case: A chai stall near a college sells tea for ₹10 per cup and sells 3,000 cups a month. Monthly costs: rent ₹8,000, ingredients ₹4 per cup, helper's pay ₹6,000. The owner asks: "How much am I actually making, and how do I make more?"
How a consultant thinks through it:
- Start with the question. Profit = money coming in - money going out. Write that down before calculating anything.
- Revenue: 3,000 cups x ₹10 = ₹30,000 per month.
- Costs: ingredients 3,000 x ₹4 = ₹12,000, plus rent ₹8,000, plus helper ₹6,000. Total ₹26,000.
- Profit: ₹30,000 - ₹26,000 = ₹4,000 per month.
- Recommendation: profit comes from three levers - price, number of cups, and costs. For example, at ₹12 per cup (if customers accept it) profit becomes 3,000 x 8 - 14,000 = ₹10,000. State the lever you'd pull first and why.
That is the whole game: define the question, break it into parts, do the math out loud, end with a clear recommendation. Every big case is this pattern with more branches.
Jargon buster
- Framework
- A ready-made checklist for thinking (like "revenue - costs"). Tools, not rules.
- MECE
- "Mutually exclusive, collectively exhaustive" - split a problem into parts that don't overlap and cover everything.
- Hypothesis-driven
- Make an educated guess early, then test it, instead of exploring everything equally.
- Issue tree
- A branching diagram that breaks the big question into smaller questions.
- Market sizing / guesstimate
- Estimating a number ("how many cups of chai are sold in Delhi daily?") with logic and rough math.
- Interviewer-led vs candidate-led
- McKinsey-style interviews guide you through set questions; BCG/Bain-style expect you to drive the structure. Formats vary by role and office.
Prefer watching? 🍿
Full beginner video lessons are in the Caseflix 🍿 tab - start with stage 1.
Help & FAQ
How each part of Case Cracker works, honestly - including what it can't do yet.
Is Case Cracker free?
Yes. Every section - frameworks, cases, analyzer, resources - is free to use, no card needed.
Do I need an account?
No. Everything works without logging in. With a free account, your case history and progress are your case history (cases opened, analyzer runs, solutions viewed) is saved to your account in the cloud, visible only to you after login - it follows you across devices. Highlights and underlines are different: they are stored only on the device where you made them, separately per account on that device, and are never uploaded. Accounts are being rolled out - if login isn't available on your device yet, nothing else is affected.
How does the Case Analyzer work?
It is a rule-based study guide, not a live AI. It matches your problem to one of 7 common case types using keywords, then recommends frameworks and steps from standard consulting methodology. It runs entirely on your device - your text is not sent anywhere. Limit: keyword matching can misclassify unusual or mixed cases, so treat its output as a starting structure, not gospel.
How does photo scanning work?
"Take a photo" opens your camera (on phones) and "Upload an image" picks a file. The text is read on your own device - the image is never uploaded. It works on clear printed text; handwriting is not reliable.
Where do the cases come from?
Two kinds: official free practice cases from firm websites (linked, with solutions on the firms' own sites), and original fictional practice cases written for Case Cracker - always labeled "original".
What is "Ask AI"?
Ask a doubt about a specific case and get a simple explanation that uses that case as context, inside the app. It is currently in private testing on selected accounts; answers can be wrong, so the worked solution stays the checked reference. Unlike the Case Analyzer (which runs on your device), Ask AI sends your question and the case text to Google (Gemini) to write the answer - anything you type in the question goes to Google, so skip personal details. Your login email and activity history are not sent.
Who can see my progress?
Only you. Progress is stored per-account with per-user access rules enforced by the database. When you're logged out, nothing is saved at all.
Who made this?
Case Cracker is a student-built prep tool. Firm and school names belong to their owners; linking to their free material doesn't imply endorsement.
The lore 🎀
Bhumika Sharma
Founder, Case Cracker
I'm Bhumika Sharma. English Honours undergrad, now doing my MBA at Masters' Union. Went from "what does the author mean?" to "what does the client want?" Different syllabus. Same confusion.
So I built Case Cracker. Because staring at a case until it solves itself was, unfortunately, not a strategy.
The app is pink because "I'm just a girl in the world" 🎀
The questions have no intention of being nice.
Contact Us 💌
Questions, feedback, or a case you'd love to see? Write to us:
bhumikashara20@gmail.comTake me on a coffee ☕
Case Cracker is a student-built prep tool. If it helped you, an optional way to say thanks is on the way.