Question

How does knowing ways to arrange 18 chairs in equal rows help you find factors of 18?

Answer 1

So that each row can have the same number of chairs.

18 = 1 x 18
18 = 2 x 9
18 = 3 x 6

so we can arrange them:

1 row of 18 chairs
2 rows of 9 chairs
3 rows of 6 chairs