Using binary operator in a sentence

Question

\documentclass{article}
\usepackage{graphicx}

\begin{document}

\title{GROUP THEORY}

\maketitle

\section{Algebraic System}
It defines on binary operator \star  over a set A such that A \star A \rightarrow B

If the operator results in the same set that it operates upon, then the algebraic system is called "CLOSED"

Eg:
\begin{enumerate}
    \item Set of integers is closed under +,-,\star\ operator.\
    \item Set of integers is not closed under / operator.\
\end{enumerate}


\end{document}

i want

Group Theory

Algebraic System: It defines on binary operator * over a set A such that A * A --> B

Eg 1. set of integers +,-,* 2.set of integers /

(i want to replace * with star operator \star)

Answer 1

The commands you like to use are only valid in math-mode. i.e. between two $ signs:

\documentclass{article}

\usepackage{csquotes}% will help you to get real quotes ;-)
\MakeOuterQuote{"}

\begin{document}

\title{GROUP THEORY}

\maketitle

\section{Algebraic System}
It defines on binary operator $\star$ over a set $A$ such that
$A \star A \rightarrow B$

If the operator results in the same set that it operates upon,
then the algebraic system is called "CLOSED"

Eg:
\begin{enumerate}
    \item Set of integers is closed under $+$, $-$, $\star$ operator.
    \item Set of integers is not closed under $/$ operator.
\end{enumerate}
\end{document}

In LateX you should declare everything that is math as such. That means that you use $…$ or \(…\) for inline and \[…\] the {equation} environment (or one of the many other math environments) for display math.

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BTW: "CLOSED" won’t give you the right quotes. If you load csquotes and define " as quotation markers with \MakeQuterQuote you’ll get the right symbols in your PDF …