I was reading this question: How do you find the area of a parallelogram with the vertices?
$A_\text{parallelogram}= \left|\vec{AB}\times\vec{AD}\right| = \left| \begin{pmatrix}4\\2\\0\end{pmatrix} \times \begin{pmatrix}9\\6\\0\end{pmatrix} \right| = \left|\begin{pmatrix}0\\0\\6\end{pmatrix} \right| = 6$
the part I dont understand is how is $(4,2,0) \times (9,6,0)= (0,0,6)$ whats the arithmetic behind the formula?