[garciansmith]

It would depend on the age of the typewriter, even the US. Many early ones did not have dedicated keys for symbols, which were made as the parent describes: by going back and typing another character over them (e.g., S backspace / to get a dollar sign).

[kragen]

Sure, I used one back in the 01980s where "!" was "'." with a backspace in between to overstrike them. And of course that's also what _, ^, `, etc., are for.