What's a quick and useful reference, either in print or online, for writing numbers and reporting measurements in scientific texts? Something I could distribute to all new students, which would cover things they should be taught but do not always know, like:

  • how to write big/small numbers in scientific form (1.78 10–12), including proper spacing?
  • how to write units of measurement, in text and in abbreviated form? includes: when do you capitalize units, when do you pluralize them, etc.
  • how to properly report significant figures, etc.
  • when do you write variables in italics/roman/bold/underline?

3 Answers 3


I guess these recommendations by the American Physical Society might be just what you are looking for. In particular, Style and Notation Guide for Physical Review/Physical Review Letters deals with scientific numbers, units, figures/tables, and use of roman/italic fonts. (For some strange reasons, it requires a secured connection to see the file; in case you couldn't see it, there is an excerpt here).


The American Chemical Society offers an online version of its ACS Style Guide. While this used to be available only in print, it is now apparently being distributed free of charge—or at least is available at any university with a subscription to ACS Journals. However, since it's intended to be a resource for anyone planning to submit to an ACS journal, I suspect it's generally available. The link above will take you to the specific chapter on math and units of measure.


The SI unit brochure (BIPM) is actually quite clear and well-written, and backs up many of its points with logical/physical justification. I would say the style guides (should) build on this.

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