to switch the ( ) around and make the multiplication easier. 10 x (4 x 2) is easier then (10 x 4) x 2.
4 times 2 is eight and 10 times 8 is 80. They way the ( ) show it is 10 x 4 is 40 and then 40 times 2 is eighty. either way you get the same answer, but it may be easier to work with 4 times 2 for some people.
