Hello Wolfgang,
My PMP exam was almost two years ago so I don't know how things are right now, but there were significantly fewer questions -- if any -- than on this platform that required the candidate to have memorized formulas or to do complex calculations. I hope others who have take the exam more recently can chime in and give you an up-to-date feel for things. I never needed to open the calculator tool during my exam and barely used the note-taking materials (and I'm no genius-level human calculator). From my understanding, the PMI changed the exam a year or so prior to that. Before then, there was more of an emphasis placed on having learned formulas off by heart, memorizing the processes and ITTOs, etc.
This is not to say that there is no need to be familiar with the large number of formulas used in project management. It's just impossible to know which you might be called upon to apply in the 180 questions that you come up against in the PMP exam. I know that this isn't particularly useful to you for preparing to take the exam. Personally, I'd err on the sid of caution and over-prepare than under-prepare... but only you know how much time you have at your disposal.
