There are sites such as OptionsHouse and TradeKing which offer trades for as low as $4. This is less than half of what's offered from the big brands.

Are there any catches or things I should know about before using such sites? Are their brokers  equally effective?


Question: Adding slides to previous section - Beamer
Answer: USe only two \section command and also the possibility of a title for the frame:

\documentclass{beamer}
\usetheme{Frankfurt}
\usecolortheme{lily}
\usefonttheme{professionalfonts}
\usepackage[english]{babel}
\beamertemplatenavigationsymbolsempty
\setbeamerfont{page number in head/foot}{size=\tiny}
setbeamertemplate{footline}[frame number]

\begin{document}

    \section{Numerical examples}
    \begin{frame}
    Example 1
    \end{frame}

    \begin{frame}{Results}
    Results 1
    \end{frame}

    \section{Numerical examples}
    \begin{frame}
    Example 2
    \end{frame}

    \begin{frame}{Results}
    Results 2
    \end{frame}

\end{document}