Microsoft Excel is a fantastic tool for analyzing scientific data. Microsoft Word is a fantastic tool for writing up scientific research. So surely Microsoft Office is the only software a scientist would ever require beyond that associated with specialist scientific apparatus? Unfortunately, that has never been the case and most university researchers would identify one big problem with the Office suite and that is why it‘s always been difficult to present formulas in Word and Excel. Even when you type a simple fraction like 3/5, it gets presented on a single line. As for Greek symbols like pi...well, that would mean many hours wasted trawling through Excel‘s Insert Symbol menu.
Overall most people tend to learn better this way rather than trying to learn all Excel formulas at the same time as this can be very confusing. Most of us tend to learn in smaller packages of information and you should look for a course of instruction that will allow you to do this. As you are learning to use Excel you should of course start by learning to use the formulas that you are actually using or are likely to have need of in the immediate future.