How to improve my approach to math problems?

Hi Floyd!

when approaching the quant part of a case, it is important to think of it as a "mini case", as the approach would be exactly the same:

1. Take some time at the beginning to structure the problem. Define the question clearly (in this case: What do you want to calculate, using the data you have).
2. Then develop a framework (the equation) and take the interviewer along by telling them what you will calculate. In a face-to-face meeting, you can show them the equation to take them along, through zoom you need to overinvest in this stage. End with the question on whether this makes sense or the interview would have any comments.
3. Once aligned on the equation, execute the math. During the execution, pay attention to potential short-cuts. Often you don't need to make the complex written division if you see a short cut. Confirm with the interviewer if it's OK to make simplifications (e.g. calculating with +-5% accuracy, multiplying with 100 instead of 97, etc), rather than calculating the last digit. If you are insecure about your mental and written math skills and about seeing these shortcuts, there are many resources on practicing this. GMAT resources are a good start. 
4. Before you communicate your results, do a quick mental sense check. Is the number in the right ballpark, or does it feel completely out of whack? If it feels wrong, tell the interviewer about your result, but that it doesn't feel right so you want to double-check for potential sources of error.
5. Communicate your results and give the interviewer the chance to react before using it in your next steps.

To practice this (as opposed to just the execution), practice with the available cases here on Preplounge and tell your case partners to pay special attention of your handling of the quant section.

I hope this helps. If you need someone to practice this in a systematic way, feel free to DM me.

Hey Floyd,

Some great answers from a variety of angles have already been asked. Check these out!

Mental Math

https://www.preplounge.com/en/consulting-forum/mental-math-help-7962

https://www.preplounge.com/en/consulting-forum/is-quick-mental-math-a-skill-that-can-be-learned-5210

Conceptual/Contextual Math

https://www.preplounge.com/en/consulting-forum/materials-for-practicing-conceptual-case-math-8016

https://www.preplounge.com/en/consulting-forum/math-concepts-6951

Key Math Equations

https://www.preplounge.com/en/consulting-forum/math-equations-their-use-7934

Math Practice

https://www.preplounge.com/en/consulting-forum/case-math-practice-6877

Hi Floyd,

It would be good to add a bit more context what specifically your problems are right now.

Generically speaking, do the following in a case interview:

1. Develop a conceptual structure how to approach the math
2. Communicate and align that with the interviewer (this is important before actually doing the math - in case you have a conceptual error in your logic, it's still easy to correct and you didn't yet spend a lot of time figuring out a wrong result, and the interviewer can much easier follow your steps which is client-friendly behaviour)
3. Insert the numbers and do the actual math
4. Do a reverse calculation or sanity check if your result actually makes sense (quite embarrasing in front of c-level execs to say out a number which is obviously wrong)
5. Think about the bigger picture/context of what this result means for your case/analysis
6. Communicate it appropriately

Side note: since the human brain is not capable of real multi-tasking in terms of parallel processing, this structured step-by-step approach is not only client friendly but also minimizes the risk of simple stupid math mistakes if you keep the conceptual part separated from the actual execution of the math.

Hope this helps - if so, please be so kind to give it a thumbs-up with the green upvote button below!

Robert

Hi Floyd,

This is what I would recommend for a math problem:

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

Hope this helps,

Francesco

Hi Floyd,

What math problems do you have specifically?

In general, I would recommend the following approach:

1. Determine the structure and all the necessary information you need to consider to make your calculations.
2. Clarify with the interviewer all the details before you start calculations. Share what you are going to do.
3. Do the first computations. 
4. Perform them to the interviewer. It is important to keep the interviewer aligned along the whole process so he/she can provide you immediate feedback and approval.
5. Use some seconds to quickly check your results before you finally present them to the interviewer.
6. Share the results and suggest the next steps on their basis.

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GB