enumerate in multicols

Question

The following image illustrates what am looking for:

Essentially I want the numbering to occur as shown above but using the multicol and enumitem package. But when I try it by using the following code:

\documentclass{article}
\usepackage{amsmath,amssymb}
\usepackage{enumitem,multicol}
\begin{document}
\begin{enumerate}
\item Evaluate each of the following if $x$ is a non-zero real number.
    \begin{multicols}{2}
    \begin{enumerate}[itemsep=1cm]% The item sep is my choice here.
    \item $\dfrac{|x|}{x}$
    \item $\dfrac{x}{|x|}$
    \item $\dfrac{|-x|}{-x}$
    \item $|x|-|-x|$
    \end{enumerate} 
    \end{multicols}
\end{enumerate}
\end{document}

I get:

Essentially, I want the (b) to be where the (c) is. I know this has been done but I can't seem to find it.

Answer 1

\documentclass{article}
\usepackage{amsmath,amssymb}
%\tracingall
\def\horizlist#1#2#3{%
  \setcounter{enumi}{0}%
  #3%
  \flushleft
  \dimen0 \linewidth
  \divide\dimen0 by #1\relax
  \advance\dimen0 -#2\relax
  \def\item{\hfil\egroup\penalty50 \hfill
  \refstepcounter{enumi}%
  \leavevmode\hbox to \dimen0 \bgroup\space(\theenumi)\space}%
  \leavevmode\bgroup\hskip 0pt plus -1fill }

\def\endhorizlist{\hfil\egroup\endflushleft}

\begin{document}
\begin{enumerate}
\item Evaluate each of the following if $x$ is a non-zero real number.
    \begin{horizlist}{2}{1cm}{\renewcommand\theenumi{\alph{enumi}}}
    \item $\dfrac{|x|}{x}$
    \item $\dfrac{x}{|x|}$
    \item $\dfrac{|-x|}{-x}$
    \item $|x|-|-x|$
    \end{horizlist}
\end{enumerate}
\end{document}

---

To see what is happening here, if you want the numbering to go right-left before down that is normal paragraph word order so the thing to do is just make a series of boxes of fixed width If they are (say) 1/3 of text width and you makes a paragraph of such boxes in a flush left paragraph then Tex will naturally wrap the paragraph with three boxes on a line and they will align vertically as they are all the same width. the rest of the code just increments a counter and puts (\the...) at the front of the box, and hides the \makebox[0.3\textwidth]{...} syntax to use the standard \item syntax so it is easy to switch between list types.

In other words compare to the following which is the same apart from cosmetic syntax changes.

\documentclass{article}

\begin{document}
\begin{flushleft}

\makebox[.3\textwidth][l]{one one}
\makebox[.3\textwidth][l]{two 2 two 2 two}
\makebox[.3\textwidth][l]{three three 3}
\makebox[.3\textwidth][l]{4 4 4 4 4 }
\makebox[.3\textwidth][l]{fifth box}
\makebox[.3\textwidth][l]{number 6}
\makebox[.3\textwidth][l]{7 7 7 7 }
\makebox[.3\textwidth][l]{eight}
\makebox[.3\textwidth][l]{nine nine}
\makebox[.3\textwidth][l]{10}

\end{flushleft}
\end{document}

Even though the result has the appearance of being in three columns, it is just a typeset paragraph with the alignment being automatic as each "word" in the paragraph is a box of equal size.

Answer 2

Here is an option using the defined \newitem command. The contents is set in a \parbox that naturally flows left-to-right, providing the enumeration in the style you're after:

\documentclass{article}
\usepackage{amsmath,amssymb}% http://ctan.org/pkg/{amsmath,amssymb}
\usepackage{enumitem,multicol,setspace}% http://ctan.org/pkg/{enumitem,multicol,setspace}
\newcounter{subenum}[enumi]
\renewcommand{\thesubenum}{\alph{subenum}}
\newcommand{\newitem}[1]{%
  \refstepcounter{subenum}%
  \parbox{\dimexpr.5\linewidth-.5\columnsep}{%
    \makebox[\labelwidth][r]{(\thesubenum)\hspace*{\labelsep}}%
    #1}\hfill%
}
\begin{document}
\begin{enumerate}[start=8]
  \item Evaluate each of the following if $x$ is a non-zero real number.
    \begin{multicols}{2}
      \begin{enumerate}[itemsep=1cm]% The item sep is my choice here.
        \item $\dfrac{|x|}{x}$
        \item $\dfrac{x}{|x|}$
        \item $\dfrac{|-x|}{-x}$
        \item $|x|-|-x|$
      \end{enumerate} 
    \end{multicols}
  \item Evaluate each of the following if $x$ is a non-zero real number.\par
    \setstretch{3}%
    \newitem{$\dfrac{|x|}{x}$}
    \newitem{$\dfrac{x}{|x|}$}
    \newitem{$\dfrac{|-x|}{-x}$}
    \newitem{$|x|-|-x|$}
\end{enumerate}
\end{document}

Spacing consideration is provided by setspace and can be tweaked (also removing some additional "\topsep" white space, if needed).

---

For a slightly more automated approach to changing the number of columns, add

\usepackage[nomessages]{fp}% http://ctan.org/pkg/fp

to your document preamble, and use

\FPeval\thecolwidth{round(1/4:4)}% Specify number of columns -> column width
\newcommand{\newitem}[1]{%
  \refstepcounter{subenum}%
  \parbox{\dimexpr\thecolwidth\linewidth-.5\columnsep}{%
    \makebox[\labelwidth][r]{(\thesubenum)\hspace*{\labelsep}}%
    #1}\hfill%
}

as your definition for \newitem. Modify 1/4 to 1/<col nums> to increase the number of columns.

Answer 3

This is easy with the exsheets package and the tasks package. The following example hopefully is self-explaining:

\documentclass{article}
\usepackage[T1]{fontenc}

\usepackage{mathtools}
\DeclarePairedDelimiter\abs{\lvert}{\rvert}

\usepackage{exsheets}% loads the `tasks' package
\SetupExSheets{
  headings = runin-nr
}
\settasks{
  counter-format = tsk[a]. ,
  label-format = \sffamily\itshape\bfseries
}

\setcounter{question}{43}% only for this example

\begin{document}

\begin{question}
  Evaluate each of the following if $x$ is a non-zero real number.
  \begin{tasks}(2)
    \task $\dfrac{\abs{x}}{x}$
    \task $\dfrac{x}{\abs{x}}$
    \task $\dfrac{\abs{-x}}{-x}$
    \task $\abs{x}-\abs{-x}$
  \end{tasks}
\end{question}

\end{document}

Answer 4

Here is another solution which does not have to define a new \item command.

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath,amssymb}%for \dfrac
\usepackage[inline]{enumitem}%for enviroment enumerate*
\usepackage{tabto}%for \tab and \NumTabs
\begin{document}
\begin{enumerate}[start=44]
\item Evaluate each of the following if $x$ is a non-zero real number.\\
  \NumTabs{2}
  \begin{enumerate*}[itemjoin=\tab]
  \item $\dfrac{|x|}{x}$
  \item $\dfrac{x}{|x|}$
  \item $\dfrac{|-x|}{-x}$
  \item $|x|-|-x|$
  \end{enumerate*}
\end{enumerate}
\end{document}

Here is what the solution looks like

The command \NumTabs{2} is a to specify that there should be two tab stops, this uses the current value of \linewidth to create tab stops for the rest of the document.
Thus if the line width changes and if you need to use tabs, then it is best to rewrite \NumTabs{2}. The command \tab makes the text that follows it to be positioned at the next tab stop.

The environment enumerate* is used to create inline lists, thus I put a \\ after "is a non-zero real number." The option itemjoin is used to specify what comes between the items, in this case the command \tab comes in between each item.

Answer 5

Here is a boring one that uses the resume functionality of enumitem package. It's not the most efficient as the code starts stops the enumerate environment too much. But the result is acceptable visually. You can introduce all kinds of additional tweaks since it's just a tabular environment.

\documentclass{article}
\usepackage{amsmath,amssymb}
\usepackage{enumitem}
\newcommand{\Choices}[4]{\begin{tabular}{p{0.5\textwidth} p{0.5\textwidth}} 
\begin{enumerate*}[series=lafter]
    \item #1
\end{enumerate*} &%
\begin{enumerate*}[resume=lafter]
    \item #2
\end{enumerate*} \\[2\baselineskip]
\begin{enumerate*}[resume=lafter]
    \item #3
\end{enumerate*} &%
\begin{enumerate*}[resume=lafter]
    \item #4
\end{enumerate*}
\end{tabular}}

\begin{document}
\begin{enumerate}
\item Evaluate each of the following if $x$ is a non-zero real number.

\Choices{$\dfrac{|x|}{x}$}{$\dfrac{x}{|x|}$}{$\dfrac{|-x|}{-x}$}{$|x|-|-x|$}

\item Evaluate each of the following if you can.

\Choices{This question is not answerable (is that a real word?)}
{This question does not have any correct answer}
{$\int_0^\pi{\tan\sqrt\theta d\theta}$}
{Whatever is a valid answer!}
\end{enumerate}
\end{document}