How can I assign an equation number to this matrix equation?

I want to assign an equation number to the following matrix equation; I want a number in brackets on the right side, after the equation.

$\begin{bmatrix} 1 \\ 2 \\ 3 \\ \end{bmatrix}$


But adding  around this throws an error at $. How can I number this matrix equation properly? • use equation instead of \[$ not in addition to it. Sep 29 '16 at 16:04

Replace $ with and $ with .
\documentclass{article}
$$\begin{bmatrix} 1 \\ 2 \\ 3 \end{bmatrix}$$

For more on $...$, the equation environment, and still other methods for creating displaystyle equations, see What are the differences between , \[, align, equation and displaymath?