Formulae don't work for me in Calc

I just get the text of the formula in the cell. All similar questions about this have been closed by Alex, because it has already been answered but how do I find the answer (Alex seems to have answered 711 questions to date, do I have to scroll through all these answers?)

If a thread is closed, the answer(s) is (are) still present. Simply read!
By the way: Alex Kemp “accepted” answers to many questions neither originally posted by himself nor answered by him. It was kind of cleaning up.

Did you enter the formulae correctly starting with an equal sign =?
If so, most likely the cells have the (fake) ‘Numbers’ format ‘Text’ (format code @).
Do you know the >View’ > ‘Value Highlighting’ (Ctrl+F8)? If you activate this: What type (text colour) is the cell containing your formula?
If this did not help to clear things, please report to more detail: What did you already try? Do you get the issue also with a completely new Calc document? …

See also ToolsOptionsCalcViewDisplayFormulas (untick if necessary)

Regards