Answer:
Step-by-step explanation:
The upside down exclamation point(¡) denotes the subfactorial in math. There are two ways to approach solving the subfactorial, one being exact, while the other is a more practical approach.
One way (the mathematically correct way) is using the formula:
n=n!∑[(-1)^k]/k!, where k starts at 0 and counts to n.
However, another, less accurate way is simply ¡n = [n!/e], where the brackets mean to round to the nearest integer, which returns 2.25268983 * 10^(103)
Hope it helps :) and let me know if you want me to elaborate, or if the notation used was intended to be something else, as the subfactorial of 72 seems like an unnecessary amount of tedium.