Added notes PAR

.gitignore

@@ -1 +1,3 @@
 credentials.txt
+*.aux
+*.log

1/PAR/introduction.txt

@@ -1,2 +1,8 @@
 Professor: Pedro Miguel Santos Luna
 E-Mail: pmsantos@ceuandalucia.es
+
+## Numbering Systems
+ - Decimal (10)
+ - Binary (2)
+ - Octal (8)
+ - Hexadecimal (16)

1/PAR/unit0.tex

@@ -0,0 +1,22 @@
+\documentclass[12pt]{article}
+
+\title{Unit 0: Introduction}
+\author{Nicolás A. Ortega Froysa}
+
+\begin{document}
+\maketitle
+
+\section{Numbering Systems}
+Generally we will work in 4 numbering systems:
+
+\begin{itemize}
+	\item Decimal (base 10): notation $x_{10}$
+	\item Binary (base 2): notation $x_{2}$
+	\item Octal (base 8): notation $x_{8}$
+	\item Hexadecimal (base 16): notation $x_{16}$
+\end{itemize}
+
+The \textbf{binary} system is used for computers since digital/electronic
+signals can only be on (1) or off (0).
+
+\end{document}