It isn’t so much about remembering as understanding the concept that the formula conveys. In that regard they are all important, but I don’t think the formulae are testable as standalone questions. Probably help you analyze a table etc.
I would also add being able to derive/manipulate the formulas - given the inputs to 1 can you solve for one of the other formulas/inputs. That seems to be a big tester on the practice exams.