math
posted by cherry .
if you know that 7* 8=56 , how can you use the commutative (Order) Property of Multiplication to find the product of 8*7 ?

you just did. The property means that
8 * 7
is exactly the same as
7 * 8
In other words the two factors commute, you can change their order without changing their product. This will be true until you get to multiplying matrices. 
http://coolmath.com/prealgebra/06properties/02propertiescommutativemultiplication02.htm

Remember back when when you were learning addition you had the commutative property of addition which means
2 + 3
is the same as
3 + 2
Now you are getting the same property for multiplication :)