[Tex/LaTex] How to change the chapter number to display as text (One, Two, …)

chaptersnumberingsectioning

In LaTeX, how do I change the chapter number to display as text? eg:

CHAPTER ONE not CHAPTER 1;

CHAPTER THIRTEEN not CHAPTER 13.

Best Answer

Short answer: put the following code before \begin{document}.

\usepackage{fmtcount,etoolbox}
\makeatletter
\patchcmd{\@makechapterhead}{\thechapter}{\Numberstring{chapter}}{}{}
\patchcmd{\chaptermark}{\thechapter}{\NUMBERstring{chapter}}{}{}
\makeatother

Change \Numberstring into \numberstring if you don't want the number name capitalized.

A longer answer requires more information from you, that you can add to your question.

A quick solution would be also

\usepackage{fmtcount}
\renewcommand{\thechapter}{\Numberstring{chapter}}

but this will have some consequences on the typesetting of the Table of Contents (but also of headers). Choosing a strategy depends on the actual needs (and also on the class used).