I just figured out a new way of doing it using your wonderful math and logic. Simply put, this removes nearly all restrictions (Excluding Roblox’s float number limit)
local LetterChars = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"}
function ConvertNumToChars(num,Characters)
num = tonumber(num) or 1 --To make sure that the number inputted is a number.
Characters = Characters or 3 --Making sure there's a specified number of characters wanted.
local Str = ""
for i=1,Characters do
local Letter = LetterChars[num % 26 + 1]
Str = Letter..Str
num = math.floor(num / 26)
end
return Str
end