In LaTeX, how do I change the chapter number to display as text? eg:
CHAPTER ONE not CHAPTER 1;
CHAPTER THIRTEEN not CHAPTER 13.
Short answer: put the following code before
A longer answer requires more information from you, that you can add to your question.
A quick solution would be also
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).
Alternatively, also view some of the self-created code on Vincent Zoonekynd's LaTeX page for Chapters.