How do you add degrees of vectors?

$$\begin{pmatrix}
1 \\
2
\end{pmatrix} %
+%
\begin{pmatrix}
3 \\
4
\end{pmatrix} %
=%
\begin{pmatrix}
1+3 \\
2+4
\end{pmatrix} %
=%
\begin{pmatrix}
4 \\
6
\end{pmatrix}$$

.