I just had the first interview of the final round at McKinsey and I'm not sure if i will make it. I'm currently working in another sector (at a law firm) but my dream job was always McKinsey.
The feedback I received from previous rounds was that my PEI was incredibly strong and I was really good at math but sometimes i rushed on calculations and I should take a pause and do it slowly.
Then, the first interview of the final round happened:
PEI: I told a story about how i faced one of the biggest problem my office had to face and i came up with a conclusion that not only saved the day but changed the way the whole industry works (not only our client). The partner asked me what was the complex part in that because the way i told him seemed pretty easy. I somehow managed to say that simple ideas usually seem easy a posteriori, but wasn't at that moment (i.e Facebook).
Case: did pretty well until the maths. i had to calculate three diferrent things then add them together and compare it with other data. I asked for 30 seconds to think the approach and realize i needed one extra data; which he provided me. I started the calculations and everything was smooth until the last thing i had to calculate. I came up with a equation (which was correct) and screw up multiplying something like 3x2 so the answer didn't make sense which i said outloud. I asked for a second and change my mind and design another different equation and solved it well but the partner told me that it was better the first one so i went back at it, realized where i made the mistake and solve it perfeclty and connected the numbers with my framework and other data. Everything else was correct.
Edit: i guided my interviewer during all my calculations and stated the things i was going to do before even starting to do them
Did i bomb the interview?