Lua supports the usual arithmetic operators:
% (modulo), and
If the operands are numbers, or strings that can be converted to
numbers (see §2.2.1),
then all operations have the usual meaning.
Exponentiation works for any exponent.
x^(-0.5) computes the inverse of the square root of
Modulo is defined as
a % b == a - math.floor(a/b)*b
That is, it is the remainder of a division that rounds
the quotient towards minus infinity.