Math Problems

case math
New answer on Dec 16, 2019
6 Answers
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Anonymous A asked on Dec 13, 2019

I noticed in my case interviews I sometimes struggle with identifying what equations to derive and use to the different math word problems. Ofcourse, there are the general profit and loss formulas that are easy to use/apply but I mainly struggle when there are complications to the units that are being used.

Does anyone else have this problem? Is it possible to improve on this? If so, how?

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Luca
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replied on Dec 14, 2019
BCG |NASA | SDA Bocconi & Cattolica partner | GMAT expert 780/800 score | 200+ students coached

I always suggest not to try remember formulas by heart. As you were saying, during the cases you have to derive easy formulas and you have just to learn to structure your thoughts in the right way.

Is just a problem of deriving the right formulas or also to do calculations?

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Anonymous A on Dec 14, 2019

Hi Luca, probably both to be honest!

Luca on Dec 14, 2019

You can improve these skills training with test like the PST. These tests require a lot of quantitative skills and you will get used to do the math part in a quick way. Contact me if you need some materials

Antonello
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updated an answer on Dec 13, 2019
McKinsey | MBA professor for consulting interviews

Hi,
I recommend practicing with Preplounge math tool (https://www.preplounge.com/de/mental-math.php) and watching the videos of this super-useful Youtube channel: https://www.youtube.com/watch?v=PYrgjMubh-c

Hope it helps,
Antonello

(edited)

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Clara
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replied on Dec 16, 2019
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut
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Deniz
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replied on Dec 16, 2019
BCG | Kearney | 350+ trainees | 5+ years of experience in London, Dubai and Istanbul

Hi,

As mentioned by other experts here, I recommend that you use the mental math tool to brush up your math skills. But furthermore, when I work with my trainees, I give them some basic homework (equations with one unknown). You can create something similar on your own, and solve them every now and then.

Best,

Deniz

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Francesco
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replied on Dec 14, 2019
#1 Coach for Sessions (4.000+) | 1.400+ 5-Star Reviews | Proven Success (➡ InterviewOffers.com) | Ex BCG | 9Y+ Coaching

Hi Anonymous,

in terms of deriving the formula and the units to use, it would be useful if you could provide an example of a problem you found challenging to provide specific suggestions.

In general terms I would recommend the following for a math problem:

  1. Repeat the question – candidates sometimes do mistakes answering the wrong question in the math part
  2. Present how you would like to proceed from a theoretical point of view (you may ask for time before presenting if you initially don't know how to approach the problem)
  3. Ask for time and perform the first computations
  4. Present interim steps to the interviewer to keep him/her aligned – don’t just say the final number
  5. Continue with the computations until you find the final answer
  6. Propose next steps on the basis of the results you found

Hope this helps,

Francesco

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Vlad
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updated an answer on Dec 15, 2019
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School

Hi,

A couple of recommendations here:

  • Never start your calculations if the interviewer is not asking for them
  • Make sure you understand what is the metric system(e.g. if the interviewer is talking about number of people in a queue, you should not calculate people per hour)
  • Make sure you understand the objective and the final number you have to get
  • Try to calculate first As Is and then To Be

Finally - the best way to practice is taking all casebooks available online and going through the math problems there. There is a limited number of math problems types in cases

Best!

(edited)

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Anonymous on Dec 14, 2019

Hi Vlad, to your first point, shouldn't you know when to calculate without the interviewer asking e.g. when you want to quantify something? To your second point, I'm unsure about what you mean by your example. Could you please clarify?

(edited)

Vlad on Dec 15, 2019

1) Very often candidates start doing the calculations when they see any numbers, however it's not required. 2) If the objective is the size of the queue (number of people) you should not calculate people per hour

Luca gave the best answer

Luca

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