For any two matrices A and B \[|AB|=|A||B|\]
This means determinants of products of two matrix is equal to product of determinat of individual matrix.
let A=\[ \begin{bmatrix}2&1\\5&3\end{bmatrix}\] and B=\[ \begin{bmatrix}0&1\\2&3\end{bmatrix}\]
then \[ det(AB)=|A||B|\]=-2
\[ |A|=\]\[ \begin{vmatrix}2&1\\5&3\end{vmatrix}\]=1
\[ |B|=\]\[ \begin{vmatrix}0&1\\2&3\end{vmatrix}\]=-2
