Try this with your old classic series HP.
(Hint it works best with an HP-35 because there is no
0 before the decimal mark.) This was taught to me in the '70s by an Aerospace engineer.
On the 25'th day of December
Santa entered his home.
[25] [ENTER]
Mrs. Claus wanted to make a point.
[.]
Santa said Nein, Nein, Oh Oh Oh Oh Nein! Nein!
many many times
[99000099] [X]
Mrs Claus said I'll have to get over that.
[1/X]
And Santa said.....(Turn display upside down)
Enjoy