If $\det \mathbf{M} = -2,$ then find $ \det (\mathbf{M}^4).$
We have that $\det (\mathbf{M}^4) = (\det \mathbf{M})^4 = \boxed{16}.$
We have that $\det (\mathbf{M}^4) = (\det \mathbf{M})^4 = \boxed{16}.$
The final answer is $16$. I hope it is correct.