## Counting the Power Set of a Finite Set

https://www.youtube.com/watch?v=MW7_7OAe330 If we know that the cardinality of a finite set is $n$, what is the cardinality of its power set? It turns out that there is a simple formula, which is $2^n$. We prove this fact in this video using the weak multiplication principle and bijection principle from combinatorics.