Cardinality of Set of Bijections

Theorem
Let $$S$$ and $$T$$ be sets such that $$\left|{S}\right| = \left|{T}\right| = n$$.

Then there are $$n!$$ bijections from $$S$$ to $$T$$.

Proof
Follows directly from Cardinality of Set of Injections and Same Cardinality Bijective Injective Surjective.