Answer
$72=2^3\times3^2$
Work Step by Step
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.
$72=2\times2\times2\times3\times3=2^3\times3^2$
