You might be confusing the associative property with the commutative property (I do this all the time): associative: (a + b) + c = a + (b + c) commutative: a

You might be confusing the associative property with the commutative property (I do this all the time): associative: (a + b) + c = a + (b + c) commutative: a + b = b + a For example, appending strings is associative, but not commutative. Appending items to an unordered set is both associative and commutative.