**YES** c(**AB**) = (c**A**)**B**
for scalar c.

Recall that c**A** means that every element of **A** is multiplied by c.
Here is a demonstration of the rule:

Often a matrix-matrix multiplication can be simpified by factoring one of the matrices. See the question.

Compute the following:

10 0 20 20 40 10 0 20 10-2 2 1 1 2 -2