Question 495382
<pre>
Given

  (2×3)×5 = 30

Move the parentheses and 6×5 becomes 2×15 which is also 30.

  2×(3×5) = 30

That's the ASSOCIATIVE principle of multiplication.

It's called the associative principle because
the parentheses around 2×3 associates the 2 with the 3, and
the parentheses around 3×5 associates the 3 with the 5.

The principle says 

If you have three things to multiply, you get the same answer 
in the end whether you associate the 1st and 2nd factors as 
you do when you associate the 2nd one with the 3rd.

Edwin</pre>