Using Sage\TeX, one can use Sage to compute things and put them into your \LaTeX{} document. For example, there are $\sage{number_of_partitions(1269)}$ integer partitions of $1269$. You don't need to compute the number yourself, or even cut and paste it from somewhere.
Here's some Sage code:
\begin{sageblock} f(x) = exp(x) * sin(2*x) \end{sageblock}
The second derivative of $f$ is
[ \frac{\mathrm{d}^{2}}{\mathrm{d}x^{2}} \sage{f(x)} = \sage{diff(f, x, 2)(x)}. ]
Here's a plot of $f$ from $-1$ to $1$:
\sageplot{plot(f, -1, 1)}
\end{document}