Explanation:
The commutative law of multiplication says that A*B = B*A, for any real numbers A,B. The order of multiplication doesn't matter.
That's why 15*3 is the same as 3*15.
This is because having 15 groups of 3 leads to 3+3+3+...+3 = 45 (imagine adding 15 copies of '3' together), and having 3 groups of 15 gets us 15+15+15 = 45 as well.
Or you could picture a rectangular table that has 15 rows and 3 columns. It has 45 inner cells. If the table had 3 rows and 15 columns, then we'd still have 45 inner cells.
