Bill if your elevator control is in the United States each of the buttons requires Braille to be ADA compliant as is required by laws.

I note that what has been stated is the building is 23 stories. Stories are something you typically count from the exterior of the building and does not necessarily mean there are 23 floors. For instance it is possible to have a two-storey high lobby that although it is two stories it is just one floor. A more likely twist to this 'challenge' is the fact that in many buildings the elevator does not serve the top-most storey. Elevators in 23 storey buildings typically have a hoist at the top of the shaft and that hoist takes up a storey. (On shorter buildings you can use hydraulic elevators which have lesser requirements at the top of the shaft). So it would be very typical that the elevator controls for our 23 storey building would at most be numbered to "22". And as per Bill's first example, if the numbering started with "G" (or "L" for Lobby) with the floor above as "1" then the numbering would only go to "21". By-the-way it is fairly typical for the top-most floor to be occupied only by a mechanical room containing things like air handling units and cooling towers. These mechanical spaces are accessed by stair from the floor below.

Regards, Ross