“Missing number, treated as zero”

In general, this means you’ve tried to assign something to a count, dimension or skip register that isn’t (in TeX’s view of things) a number. Usually the problem will become clear using the ordinary techniques of examining errors.

Two LaTeX-specific errors are commonly aired on the newsgroups.

The commonest arises from attempting to use an example from the The LaTeX Companion (first edition), and is exemplified by the following error text:

! Missing number, treated as zero.
l.21 \begin{Ventry}{Return values}
The problem arises because, in its first edition, the Companion’s examples always assumed that the calc package is loaded: this fact is mentioned in the book, but often not noticed. The remedy is to load the calc package in any document using such examples from the Companion. (The problem does not really arise with the second edition; copies of all the examples are available on the accompanying CD-ROM, or on CTAN.)

The other problem, which is increasingly rare nowadays, arises from misconfiguration of a system that has been upgraded from LaTeX 2.09: the document uses the times package, and the error appears at \begin{document}. The file search paths are wrongly set up, and your \usepackage{times} has picked up a LaTeX 2.09 version of the package, which in its turn has invoked another which has no equivalent in LaTeX 2e. The obvious solution is to rewrite the paths so that LaTeX 2.09 packages are chosen only as a last resort so that the startlingly simple LaTeX 2e times package will be picked up. Better still is to replace the whole thing with something more modern still; current psnfss doesn’t provide a times package — the alternative mathptmx incorporates Times-like mathematics, and a sans-serif face based on Helvetica, but scaled to match Times text rather better.

Distributed as part of 2etools
Examples for LaTeX Companion
The psnfss bundle

This answer last edited: 2011-06-01