Dear Pierre,
since I own a Casio25, I was able to follow the manual!
I provided the steps to calculate 5!
perhaps the beautiful Hélène of Troyes (☺) has had too much corona ...
I didn't say that you had told nonsense,
I was merely pointing out that your answer seemed unsatisfactory
(I didn’t fully understand it, which is why I replied
as I would have explained it to my students).
best regards to you, Comrade!