Get Active in Our Amazing Community of Over 450,000 Peers!

Schedule mock interviews on the Meeting Board, join the latest community discussions in our Consulting Q&A and find like-minded Case Partners to connect and practice with!

Made a math mistake and did not get corrected

7thinterview
New answer on Oct 26, 2020
8 Answers
1.6 k Views
Anonymous A asked on Sep 28, 2020

During my first round BCG interview I was doing long division and got to the wrong number (437 instead of 430.7). The interviewer didn't correct me and let me use this number for a sbusequent calculation which was then used in my recommendation.

I was curious if (most likely)...

-This means I automatically failed since I was not corrected and allowed to use incorrect results

-The interviewer let it slide since we were running out of time (and the rest of the case went smoothly)

-I did every other part of the math correctly so this division error wasn't a huge deal

-The interviewer may not have noticed the mistake

-Since the calculation is within 2% of the correct answer, my final answer (despite being incorrect by a wider margin since the incorrect division was multipled) wasn't that bad

[I know that it's very hard to determine the implications of a mistake since you weren't there, though I was hoping to get some perspectives on candidates that have made similar mistakes]

Overview of answers

Upvotes
  • Upvotes
  • Date ascending
  • Date descending
Best answer
Anonymous replied on Sep 29, 2020

Dear A,

In fact you math mistake doesn't look so huge, so there are few options: either inetrviewer didn't pay attention to it, or they have already made their decision.

BTW, it can be any decision - good or bad.

So just, relax and wait for your result.

Finger crossed.

Best,
André

Was this answer helpful?
10
Clara
Expert
Content Creator
replied on Sep 28, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut

Hi!

With the description you gave, I don´t think it was that bad.

If it´s any consolation, I made a worse one in my 2nd round McK interview and still passed.

Hope it helps!

Cheers,

Clara

Was this answer helpful?
Francesco
Expert
Content Creator
replied on Sep 29, 2020
#1 Coach for Sessions (4.500+) | 1.500+ 5-Star Reviews | Proven Success (➡ interviewoffers.com) | Ex BCG | 10Y+ Coaching

Hi there,

No one knows for sure, but it is probably 2 (The interviewer let it slide since we were running out of time).

Interviewers normally give always the same case, so he/she probably knew the answer was wrong.

The interviewer had likely already decided at that stage whether it was a pass or not, thus let it go.

Best,
Francesco

Was this answer helpful?
Anonymous replied on Sep 29, 2020

Hi Anonymous!

This does indeed not seem to be like a massive mistake. While always difficult to judge what happened exactly, the interviewer might have realized it was a minor math execution mistake (rather than a mistake in the planning) that is not answer-changing. Or maybe they just didn't notice...

Was this answer helpful?
7
Robert
Expert
Content Creator
replied on Sep 28, 2020
McKinsey offers w/o final round interviews - 100% risk-free - 10+ years MBB coaching experience - Multiple book author

Hi Anonymous,

Overall your math mistake doesn't look that bad - based on your description you could demonstrate that you are comfortable with numbers overall and the remaining case was strong, that's why I would pass you on for next round as an interviewer.

That being said - chances are also high that the interviewer did not really notice, easily possible. Even though we take recruiting seriously, honestly we are sometimes already thinking about our next client meeting or how to tackle another real-life issue, especially if the interview is going really well and don't need to pay that much attention since everything is progressing nicely. (Just stating the facts here - if that behaviour is good or not is another discussion)

So - for the time being don't worry too much about it, looks fine altogether!

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

Robert

Was this answer helpful?
Ian
Expert
Content Creator
updated an answer on Sep 28, 2020
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate

Hi there,

Highly likely that it's options 2-4 (i.e. they either didn't notice, or were fine with it given your other performance and small nature of the error).

Ultimately, it likely means they had already made up their mind (for better or for worse), so at least you can rest assured that this math mistake did not decide your fate!

(edited)

Was this answer helpful?
Gaurav
Expert
Content Creator
replied on Oct 26, 2020
Ex-Mckinsey|Certified Career Coach |Placed 500+ candidates at MBB & other consultancies

Hi A,

According to your story, the mistake was not so big, indeed, to be corrected. Especially if you were short on time.

Not much left to do but to wait for results. As long as this was the only small issue, I would not worry that much.

Do you need any further help?
GB

Was this answer helpful?
Anonymous replied on Sep 29, 2020

Agree with other experts that the math mistake is no big issue here. 437 vs 430.7 is like ~2% error. It is not critical at all if you think 80/20. So I think the result (which ever way it goes) would be mostly dependant on other factors of your interview, rather than this.

Was this answer helpful?
0
How likely are you to recommend us to a friend or fellow student?
0
1
2
3
4
5
6
7
8
9
10
0 = Not likely
10 = Very likely