## Basic College Mathematics (9th Edition)

$2^{3}$ * $3^{2}$
72 Try to divide 72 by the first prime number 2 72 = 36 * 2 Try to divide 36 by the first prime number 2 36 = 18 * 2 Try to divide 18 by the first prime number 2 18 = 9 * 2 Try to divide 9 by the prime number 3 9 = 3 * 3 So, 72 = 2 * 2* 2 *3*3 Because all factors are prime, the prime factorization of 72 is 2 * 2* 2 *3*3 = $2^{3}$ * $3^{2}$