Simple question : Why is my variable not taking away the number?

well you cant do local m = m - 1000 because the variable m is just being declared.. at run time, the statement actually looks like this m = nil - 1000.. so if variable m in m - 1000 was not declared before using it, it should through an error that says attempt to do arithmetic on global m(a nil value or something like that. or sometimes the code will just halt when it reaches that statement.

i recommend doing it like this:

local x = 500 --whatever number you want
local m = x - 1000

the above should work fine b/c x is declared before used, so the statement won't look like this on run time m = nil - 1000