Complex Numbers under Multiplication form Monoid

Theorem
The set of complex numbers under multiplication $\struct {\R, \times}$ forms a monoid.

Proof
Taking the monoid axioms in turn:

S0: Closure
Complex Multiplication is Closed.

S1: Associativity
Complex Multiplication is Associative.

S2: Identity
Complex Multiplication Identity is $1$.

Hence the result.