Guesstimates
How to prepare for guesstimates for consulting firm interviews? Can you share the guesstimates that you have been asked in the past? Or give examples?
I was asked to guesstimate the amount of tea consumed in Mumbai everyday. There are several books that go in deeper, but if you don't have time, you can prepare by watching some popular YouTube videos.
Read up Cracking the PM Interview, covered well in it. You'll get a free PDF/ebook if you search a bit for it.