Definition:Determinant/Matrix/Order 1

Definition
Let $\mathbf A = \sqbrk a_1$ be a square matrix of order $1$.

That is, let:
 * $\mathbf A = \begin{bmatrix}

a_{11} \end{bmatrix}$

Then the determinant of $\mathbf A$ is defined as:
 * $\begin{vmatrix}

a_{11} \end{vmatrix} = \map \sgn 1 a_{1 1} = a_{1 1}$

Thus the determinant of a single number is that number itself.