\begin{definition}[Definition:Determinant/Matrix/Order 1]
Let $\mathbf A = \sqbrk a_1$ be a square matrix of order $1$.
That is, let:
:$\mathbf A = \begin {bmatrix} a_{1 1} \end {bmatrix}$
Then the determinant of $\mathbf A$ is defined as:
:$\begin {vmatrix} a_{1 1} \end {vmatrix} = a_{1 1}$
Thus the determinant of an order $1$ matrix is that element itself.
\end{definition}