Lua supports the usual arithmetic operators: the binary + (addition), - (subtraction), * (multiplication), / (division), % (modulo), and ^ (exponentiation); and unary - (negation). If the operands are numbers, or strings that can be converted to numbers (see Coercion), then all operations have the usual meaning. Exponentiation works for any exponent. For instance, x^(-0.5) computes the inverse of the square root of x. 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.