Seth makes an array of six rows and nine columns. Mary makes an array of nine rows and six columns.

Question

The arrays have( the same or the different) number of items because the(associative or communicative) property.

Answer 1

Seth's array of six rows and nine columns has a total of $6\times 9=54$ items. Mary's array of nine rows and six columns has a total of $9\times 6=54$ items as well.

The arrays have the same number of items because of the commutative property of multiplication, which states that $a\times b=b\times a$. Thus, $6\times 9=9\times 6$.

So, the complete statement would be: The arrays have the same number of items because of the commutative property.