Function to return last letter from a text string

right()

i.e. - right(local!invoice, 1) would return the last 1 character from the passed string.

FYI, in case this helps, when I was new at this I usually kept a browser tab open to the Appian Documentation for All Functions - particularly text functions and math functions, and sometimes I'd just glance through to get new ideas (other times i'd need to do something and search for the right functions).