Answer:
12 x 6 x 2 gives the same result 144, whether it is calculated
as (12 x 6) x 2 or 12 x (6 x 2).
But 12 ÷ 6 ÷ 2 is not so straight forward as
(12 ÷ 6) ÷ 2 is 1, but 12 ÷ (6 ÷
2) is 4.
An operation x is associative if, when three elements are
combined, it does not matter how the brackets are placed.
(a x b) c = a x (b x c).
So multiplication
is associative but division is not. Similarly the following example
illustrate that addition is associative but that subtraction is
not.
(12 + 6) + 2 = 20 = 12 + (6 + 2)
(12  6)  2 = 4 but 12  (6  2) = 8.
