Numbers and strings

Lua 5.4 has two kinds of numbers: integer and float, and math.type(x) tells you which kind a number is. Division with / always returns a float, so 10 / 2 gives 5.0. // divides and rounds the result down, and % gives the remainder, so 250 // 4 gives 62 and 250 % 4 gives 2. That's how loot gold gets split among the members of a party.

The power operator ^ always returns a float, even when both numbers are integers, so 2 ^ 3 gives 8.0. That's why the XP formula 100 * level ^ 2 shows up in the UI as 900.0 for level 3, and math.floor turns it back into an integer. To display a float with two decimal places, use string.format("%.2f", x).

You call string functions with a colon (:), as in nick:upper(), nick:sub(1, 3), which takes the first through third characters, and ("#"):rep(5), which repeats the string. #nick gives you its length. But # and sub count bytes, not characters, and a letter like é takes two bytes, so #"José" gives 5. To count the characters in text like that, use utf8.len, and keep in mind that upper leaves é unchanged.