I'm doing homework from a particular book, and each question is numbered after the page number and the question number. For example 52.2, 52.9, 53.13, etc. (Note that they are not sequential.)
How do I do something that will work like the enumerate environment, but instead of 1. 2. 3., etc. at each \item, I put a custom number?
You could simply use the optional Argument of \item
\documentclass{scrartcl} \begin{document} \begin{itemize} \item [2.9] Foo \item [53.2] Bar \item [69.11] \end{itemize} \end{document} I hope that’s what you wanted to do …
enumerate environment (that is, in this instance, itemize and enumerate can be interchanged). Also, from a terminology perspective, these are environments. {description} seems to be more appropriate. You can also increase the label width e.g. by using the enumitem package. The genuinely insane way to do this is as follows:
\documentclass{article} \usepackage{enumitem} \makeatletter \newcommand*{\wackyenum}[1]{% \expandafter\@wackyenum\csname c@#1\endcsname% } \newcommand*{\@wackyenum}[1]{% $\ifcase#1\or52.2\or52.9\or53.13\or42% \else\@ctrerr\fi$% } \AddEnumerateCounter{\wackyenum}{\@wackyenum}{53.13} \makeatother \begin{document} \begin{enumerate}[label=\wackyenum*] \item One \item Two \item Three \end{enumerate} \end{document} This allows you to define an arbitrary list of numbers that the the enumeration will cycle through. This has the (very minor) advantage of having the spacing behave a little better. This is basically how a lot of things are done in the moreenum package. The documentation explains the procedure.
Depending on how much "non-sequential" your numbers are, and how much you need a quick & dirty solution instead of something with polish and automatism, you might get along with \addtocounter and some ad-hoc-ery involving the enumitem package:
\documentclass{article} \usepackage{enumitem} \begin{document} \begin{enumerate}[label=52.\arabic*,start=2] \item Answer % 52.2 \addtocounter{enumi}{6} \item Answer % 52.9 \end{enumerate} \begin{enumerate}[label=53.\arabic*,start=13] \item Answer % 53.13 \end{enumerate} \end{document} With a bit more work, you could make the page number (52, 53) into a counter of its own and wrap it all into a re-useable environment definition, but I think this gives you the idea of it all.
Building up on Seamus's insane answer, here is how to do the same in ConTeXt.
\defineconversion[insane][52.2, 52.9, 53.13,42] \starttext \startitemize[insane] \item One \item Two \item Three \stopitemize \stoptext To get automatically the page number you can do as follows
\documentclass[a4paper]{article} \usepackage{enumitem,refcount} \newcounter{qcount} \newenvironment{questions} {\refstepcounter{qcount}\label{qcount\theqcount}% \begin{itemize}[label=\protect\getpagerefnumber{qcount\theqcount}.\protect\qcountnum]} {\end{itemize}} \newcommand{\qitem}[1]{\def\qcountnum{#1}\item} \begin{document} \begin{questions} \qitem{2} A \qitem{25} B \end{questions} \newpage \begin{questions} \qitem{3} C \qitem{7} D \end{questions} \end{document} At each questions environment a new label is generated, so we can use it for numbering the questions. The \qitem command wants as argument the question number. Since the mechanism exploits the \label-\ref system, two runs of latex are needed.
In modification of egreg's solution you may use package perpages to have enumeration per page:
\documentclass{article} \usepackage{perpage} \MakePerPage{enumi} \renewcommand*{\theenumi}{\theperpage.\arabic{enumi}} \newcommand*{\nitem}[1][]{% \ifx\relax#1\relax\else\setcounter{enumi}{\numexpr #1-1\relax}\fi \item } \usepackage{lipsum} \begin{document} \makeatletter\@whilenum\value{page}<100\do{% demonstration of 99 pages \lipsum[\thepage] \begin{enumerate} \nitem A \nitem[7] B \nitem[19] C \nitem \lipsum[\thepage] \nitem D \end{enumerate} \newpage } \end{document} Instead of redefining theenumi you may redefine \labelenumi:
\renewcommand*{\labelenumi}{\theperpage.\theenumi} The difference is that \label/\ref will reference the number without page.
