## Prealgebra (7th Edition)

$72=2^3\times3^2$
72 is an even number, so it is a multiple of 2. $72=2\times36$ 36 is also an even number, so it is a multiple of 2. $72=2\times2\times18$ 18 is also an even number, so it is a multiple of 2. $72=2\times2\times2\times9$ 9 is the square of 3. $72=2\times2\times2\times3\times3=2^3\times3^2$