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Feedback after 1st interview for McKinsey

Anonymous A asked on Oct 14, 2019 - 2 answers

Hello all,

I've just finished the first interview of 1st round. Overall, I think it went okay, besides the mental math part. I spent a little to much time on the calculations, and almost couldnt find one of the values I calculated before that was needed for the last calculation.

The feedback I recieved was;

1- I should be more organized with my notes regarding the calculations and there were quicker ways to get to the answer. Analytical part

2- I missed to discuss a part in the case itself because I didn't include that part (distribution channels) in my structure. (The question was about declining revenue) He said that sometimes it is better to not follow a rigid structure, but think more broadly. Also to go more in depth about the branches.

He also said that these interviews are also some kind of practice, and I will get better when I do more. But other than the 2 areas discussed above, other parts he said that I did well.

What do you think that this feedback implies, do you think I will probably fail because of the mental math part? Also I have another one tomorrow, how should I tailor my practice after these feedback?

Much appreciated,

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replied on Oct 15, 2019
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Hi Anonymous,

in terms of practice based on the feedback, I would recommend the following:


In order to write better notes, my recommendation is to divide the paper into 4 areas as reported below for the first page; when taking notes, you can then put the information in the appropriate box. Sometimes you would have to go back and forth, as you may get information, objective 1, additional information, objective 2, etc.

  • top-left: who is the client
  • bottom left: initial information
  • top right: objectives
  • bottom right: structure

The vertical line should be closer to the left border and the horizontal line should be closer to the top border, so that there is more space for the structure.

Besides that, you can also improve your notes with the following:

  • Ask the interviewer to repeat in case you missed information. It is better to ask for missing information upfront rather than later
  • Do a recap after the prompt. This ensures you took notes correctly since the interviewer will correct you otherwise
  • Use abbreviations. Eg, for revenues use R, for costs use C, for increase use an arrow directed up, etc.
  • Write down essential information only. You do not have time to write everything, thus you should exercise in writing down only the necessary information. If you have a client that produces steel which has four plants, with a revenue problem, your notes could be something as Steel producer, R (arrow down), 4 plants


It seems you are using longer-than-necessary computations. One way to speed up math is to align with the interviewer upfront on what you want to do. Sometimes the interviewer is going to suggest a faster way to proceed. If you don’t align upfront the interviewer cannot help you.


There isn’t much you can do to improve last-minute on structuring besides doing a class with an experienced consultant or expert. I would recommend to review cases related to revenue problems/growth strategy, since it seems your structure is lacking there.



replied on Oct 14, 2019
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1) It can. If you are doing your calculations inefficiently- that's an indicator that you can waste time on the project.

2) For tomorrows interview work on math and clarity of your notes:

I recommend the following approach- split the main sheet into 2 parts and then the left part into 2 quadrants:

  • Upper left - initial information given at the beginning of the interview and while asking clarifying questions
  • Lower left - Your objective. The objective should be measurable and should have a timeline
  • Right part - Your structure and the whole caseflow

Also, a good practice is to put the key numbers near the corresponding buckets.

! Have a separate sheet for math calculations!

It's also important:

  1. A good habit is to guide the interviewer through your structure by showing the structure on paper. So at least the structure should look clean and clear for the interviewer. Literally, move your pen to the different elements of your structure while presenting. And very often you need to do more than one structure while solving the case.
  2. You need to have clarity with numbers to be successful at calculations.
  3. While providing the final recommendation you need to find all the key numbers quickly, in order to use them in the arguments. Thus you need clarity

All in all - having clear and organized notes have many pros while unclear notes can easily lead to failure.


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