Hi there,

Both good questions.

My view is that, although it changes by case, most folks structure their approach in 5-7 mins (inc. clarification questions etc). But frankly it doesn’t matter. I’d advise you to spend 10 mins, 12 mins, 30 mins (ok, maybe not 30 mins) structuring the case because this is where you actually solve it.

In my experience, most people do the bare minimum to try to advance through the case and get more info. Bad idea. For every minute you spend structuring and getting clearer on what could be going on you’ll save 5 mins on the analysis, and significantly improve your maths accuracy.

On your second question, you don’t need to run your interviewer through your calculations but you do need to make sure they’re following your approach. By way of illustration, I don’t see much value in saying “I multiplied 8 by 5 by 60%” but I do see a lot of value in saying “to calculate the average weekly billing time per person I multiplied a workday by 5 and assumed they were 60% utilised for billable activities”.

I encourage my students to use this approach to do 2 things: (i) bring the interviewer along the case with them and (ii) a structured layout of the logic (to themselves) they’re going to approach this math section. It’s amazing the number of times that you realise your approach isn’t quite right, you haven’t got all the numbers you need, you’re calculating weekly and not yearly numbers, etc.

Hope that helps.

Cheers,

B.

Hi there,

- What is considered an average time to set up the initial structure of the math portion of a typical case (including or excluding the time to check exhibits/discuss with interviewer)?

A few minutes. You need to move through the math/charts/exhibits effectively/efficiently.

- What would be the average run-down time to walk the interviewer through the calculations? This obviously depends on the question but would be helpful to know to which extent I need to speed up my explanations + calculations

Under 1 minute. You need to be clear + concise with your communication.

Hi there,

Don't obsess with a specific timeframe since every case is different. Make sure to practice enough to have a good rhythm to go over the data / charts, approach, calculations and conclusions.

Happy to keep talking about this in private, just send me a message.

Best,

Alberto

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Check out my latest case based on a real MBB interview: Sierra Springs

1. Quality of the answer is the critical issue here, not speed.
2. Almost always “being slow” is the result of having a confusing approach. It takes long because one is not doing it well (over-complicating, bad structure/approach to the estimation, etc.)
3. What is reasonable depends on the complexity of the question itself. Calculating 5% of 200 million is not exactly the same as estimating the global number of medium duty trucks in the world.