UCAR Communications Style Guide

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Numbers

1. Spell out numbers up to and including nine; use numerals for numbers larger than nine, including ordinals (Eighth Conference on Severe Local Storms, 12th Symposium). If numbers in the same category both greater than and less than nine appear within the same context (e.g., a paragraph), follow Chicago, 14th ed., p. 296, section 8.8, and use numerals for both: "each dropwindsonde is about 9 inches (23 centimeters) long and 3.5 inches (9 centimeters) in diameter." (Prior to fall 2002, our style was to spell out numbers up to and including ten.) [01-03]

2. Numerals are always used with abbreviated units of measure: 25 km, 1 m, etc. If the unit of measure is not abbreviated, rule 1 above applies: 12 months, six kilometers, etc.

3. Use numerals with very large dollar amounts and large fractions: $3 million, 6.28 million dung beetles. Spell out whole numbers from one to nine, except when you wish to convey a higher level of precision (editor's choice): about two million refugees, but they counted 8 million species. [See Chicago, 8.7, 8.25. revised 2/00]

4. Hyphenate numbers and units in adjectival phrases: six- month term, 20-year appointment, 9-km length, etc.

5. Insert a zero before decimal points (in numbers less than 1) except in statistical correlations, and even there if it would look peculiar.

6. To make numbers plural, add an s (with no apostrophe): 1940s, 16s, ones, fives, 10s, etc.

7. Use commas in four-digit and larger numbers except those expressing wavelengths: 3,124 years but 4120 A. Four-digit page numbers have no comma: pg. 5769; five digits or more take a comma for legibility: pg. 11,275. [revised 2/00—CR]

8. Use numerals for numbers used as nouns: a factor of 2. Zero is an exception: value of zero.

9. Avoid negative exponents whenever possible: 1.7 X l0^-5 photons cm^-2 s^-1 keV^-1 becomes 1.7 X l0^-5 photons/(cm² s keV)

Note, however, that wave numbers (the reciprocal of wavelength) are expressed with negative exponents.

10. money—See the "money" entry in the M section.

11. Units of measure:

Each UCAR Communications publication merits a different style. Each has a first choice, but exceptions may be made for precision or clarity when warranted. Note that altitude is a unique case.

—Media: first choice is U.S. customary.

—Quarterly: first choice is metric.

—Staff Notes Monthly: For scientific articles, first choice is metric, with U.S. customary in parentheses. For nonscientific articles, first choice is U.S. customary.

[2/00]

See also Chicago, 14th ed., p. 478, section 14.41 on the International System of Units (SI units).

See also Correct SI metric system usage (accessed 13 March 00) for correct SI style for using metric symbols.

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