Quick question: Using the rule of 72!

quant problems
Recent activity on Mar 18, 2019
2 Answers
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Anonymous A asked on Mar 18, 2019

Can I use the phrase "Using the rule of 72 we see that.." in a case interview? Or is it just a math trick that isn't really supposed to be so evidently exposed during calculations?

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Vlad
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replied on Mar 18, 2019
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School

Hi,

Not sure if I understand your question. You should always provide clarity on the way you are doing the calculations. I strongly recommend telling the interviewer HOW you are going to calculate something before actually starting the calculations. So yes, you should tell this to the interviewer.

Best!

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Francesco
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replied on Mar 18, 2019
#1 Expert for Coaching Sessions (3.700+) | 1.300+ Reviews with 100% Recommendation Rate | Ex BCG | 8+ Years of Coaching

Hi Anonymous,

as mentioned by Vlad, you can definitely mention you are using the rule of 72 - if you don’t, the interviewer will very likely ask you how you managed to calculate so quickly a compound growth. The interviewer may also ask you where the rule comes from, so be sure to review its origin, which is related to the natural logarithm.

Best,

Francesco

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Vlad gave the best answer

Vlad

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McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School
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