Stuff

Here is some stuff

$ P(E) = {n \choose k} p^k (1-p)^{ n-k} $

$ \mathbf{V}_1 \times \mathbf{V}_2 = \begin{vmatrix}
\mathbf{i} & \mathbf{j} & \mathbf{k} \\
\frac{\partial X}{\partial u} & \frac{\partial Y}{\partial u} & 0 \\
\frac{\partial X}{\partial v} & \frac{\partial Y}{\partial v} & 0
\end{vmatrix} $

Celtic bar?

Looks like a celtic style horizontal (in Prayer book orientation) rule?