I think he meant a “Realistic 2400” modem and you are correct on the math.
300, 600, 1200, 2400, 4800, 9600 - 54000 baud modems.
LOL!
first one I heard was given to me by a customer General Electric in 1984.
It was a 300 baud suitcase modem and they used it to connect to something they called a BBS.
The fellow who gave it me showed me how to use it.
I took it back to our office and we played with it for a week before putting on a history shelf.
I found out what all those dorks with Commodore s and TI’s where wasting so much time with.
Amazingly, porn is still the number one time waster.