diff --git a/pres/graphics/MathStuff.png b/pres/graphics/MathStuff.png
new file mode 100644
index 0000000..94531d4
Binary files /dev/null and b/pres/graphics/MathStuff.png differ
diff --git a/pres/pres.tex b/pres/pres.tex
index 6818974..e32d817 100644
--- a/pres/pres.tex
+++ b/pres/pres.tex
@@ -113,6 +113,11 @@
   \includegraphics[width=\textwidth]{graphics/XORBlock.png}
 \end{frame}
 
+\begin{frame}
+  \frametitle{Computations of the XOR-based block-version}
+  \includegraphics[width=\textwidth]{graphics/MathStuff.png}
+\end{frame}
+
 \subsubsection{Interpolation based}
 \begin{frame}
   \frametitle{Interpoly scheme}