The mathematical law stating that the value of an expression is independent of the grouping of the numbers, symbols, or terms in the expression. The associative law for addition states that numbers may be added in any order, e.g. (x + y) + z = (x + (y) + z). The associative law for multiplication states that numbers can be multiplied in any order, e.g. x(yz) = (xy)z. Subtraction and division are not associative. Compare commutative law; distributive law.