Any source for math problems cases

BCG case math GMAT MathSkills IB I'm preparing to McK coming next week Math problem
New answer on Jun 30, 2023
5 Answers
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Anonymous A asked on May 09, 2023

Hi everyone

 

I keep struggling with math problems, and I do not know how to structure an approach to solve it. I can do math fast, but if I am given a math problem, I do not know how to find the solution or build the approach for it?

 

Does anyone has good sources to practice math problems?

 

 

Thanks in advance

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Ian
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Content Creator
replied on May 10, 2023
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate

Hi there,

How to structure math in a case

  1. Have a seperate "math" scrap sheet of paper
  2. Grab a new sheet of paper every time you're entering a new phase of the case...number and title it
  3. Use tables to organize numbers
  4. Write out the equation before doing the math
  5. Never forget to write down units
  6. Circle key numbers AND write down the "so what"

How to practice math

Most casebooks have a section on math...but I wouldn't rely on this for your prep.

  1. 100% Recommend Rocket Blocks
  2. Online "Drills": (Sites like JetPunk and Preplounge)
  3. In addition to that, you can ask other PrepLoungers to case you on math-heavy cases. You can also search for those case types here and work through them yourself.

Some key math formulas/concepts:

  • Breakeven
  • NPV (with + without growth, perpituity + 1-2 years from now)
  • % Change
  • ROI
  • Margin
  • Markup
  • Inventory turnover

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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

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Paul
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replied on May 10, 2023
PL-level BCG experience (6 years)|Interviewer at BCG| 6/6 personal + 95%+ candidates offer success rate

Hi there,

regarding your question

I keep struggling with math problems, and I do not know how to structure an approach to solve it. I can do math fast, but if I am given a math problem, I do not know how to find the solution or build the approach for it?

I love the answers down from Ian and Francesco - would just add a nuance here that is important to clarify IMO, based on your wording in the question posed

“I do not know how to find the solution of building the approach” → to me there are two possibilities

a) You lack knowledge of fundamentals business formulas and/or routine case calculations refer to content below from other coaches

b) You cannot understand what is the link btw. the math problem and the business situation / the goal of the case → this is broader and I would personally address by

- Reading / practicing many cases with example math calculation related to various sectors/business problems 

- Perfecting my framework system to make sure you always know which “conceptual” buckets you are using to solve the case 

- Pay strong attention during the case to be crystal clear of how we get to the “math point”. If necessary re-iterate the goal of the math problem to the interviewer    

Hope it helps

 

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Francesco
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replied on May 10, 2023
#1 Coach for Sessions (4.000+) | 1.500+ 5-Star Reviews | Proven Success (➡ InterviewOffers.com) | Ex BCG | 10Y+ Coaching

Hi there,

Q: I can do math fast, but if I am given a math problem, I do not know how to find the solution or build the approach for it?

First of all I would recommend to isolate the exact problem you have. The issue could be related to any of the following:

  • Not having done enough drills for specific types of math questions
  • Not asking the right clarifying questions
  • Not asking for enough time
  • Misunderstanding the objective
  • Getting lost when given a lot of data

Once identified the exact problem, you can drill down on a solution for it.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

As general tips for math, this is what I would recommend:

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

Hope this helps,

Francesco

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Cristian
Expert
Content Creator
replied on Jun 30, 2023
#1 rated MBB & McKinsey Coach

Hi there, 

I wish I saw this question earlier. This is a rather common problem. 

Practice helps, but it doesn't really move the needle. What you need to change is your approach to maths. 

Feel free to reach out and I can send you a complimentary guide that explains how to break down calculation problems into steps to able to handle them.  

Best,
Cristian

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Sofia
Expert
replied on May 10, 2023
Top-Ranked Coach on PrepLounge for 3 years| McKinsey San Francisco | Harvard graduate | 6+ years of coaching

Hello,

I recommend slowing down and working on it in “practice mode” for a bit, instead of working on math problems in full case interview mode. When you get a math question, slow down. Make sure you really understand the problem set-up and instructions - if you don't, ask all the questions you need until you do. Then, take some time to try to formulate your approach. Check your approach. If it's not correct, try it again. Once you have the approach, proceed to do the calculation. Do each step slowly. Once you are done, give your answer verbally. After you finish the case, review the math problem once again, noting where you went wrong and what you needed to improve. 

 Working with a coach might also be helpful for something like this because a coach can give you pointers on what exactly you are struggling with in the math (e.g., are you misunderstanding the problem? Are you having trouble setting up the calculation? etc.) Best of luck!

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Ian gave the best answer

Ian

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