This will be a very brief summary of WP:MOSNUM, intended to eventually replace sections from 10 to 13 of WP:MOS. It should be about 40% of the current size of said sections of WP:MOS, and it won't include recommendations which are seldom useful except to editors of very specialized articles, such as those on scientific notation or non-base-10 numbers.

Numbers edit

Figures or words edit

In general, whole numbers from zero to nine are preferably written in words; greater numbers are preferably written in figures, but may also be written in words if they are expressed in one or two words. However:

  • Be consistent with comparable quantities in the same context: do not write five cats and 32 dogs.
  • Avoid juxtaposing non-comparable quantities both in figures or both in words: write seventy 20-pound banknotes rather than 70 20-pound banknotes.
  • Avoid starting sentences with figures.
  • Days of the month, years, and centuries are normally written in figures.
  • Numbers in mathematical formulas and before unit symbols are written in figures: e.g. 5 min, not five min. On the other hand, both words and figures are acceptable before spelled-out units, as in 5 minutes and five minutes.
  • Figures are usually understood to be more precise than words: in The population of Japan is 128 million people the number is an approximation, only precise to within one million; in The grant is 10,000,000 Swedish kronor, it is exact.
  • Note the difference between Every number except one (there is one exception, which is unspecified) and Every number except 1 (the number 1 is the exception.
  • In names, comply with common usage: e.g. Chanel No. 5 but Fourth Amendment.

Large numbers edit

  • Digits in numbers greater than or equal to 10,000 are normally grouped with commas every three digits, e.g. 12,345,678. (Templates such as {{val}} do this automatically.) Numbers greater than or equal to 1000 may or may not be grouped 1234 or 1,234; in particular, four-digit serial numbers such as years and page numbers are written without commas.
  • Avoid giving numbers with false precision or with more precision than needed in the context: for example, The population of Japan is 128 million people, not ... 127,953,234 people. (It is usually unnecessary to explicitly state that such numbers are approximations.)
  • When million and billion occur many times in an article, they may be abbreviated with unspaced "M" and "bn" respectively (£70M, $35bn), after spelling out the word on the first occurrence.

Decimal fractions edit

  • A decimal point is used between the integer and the fractional parts of a decimal; a comma is never used in this role (6.57, not 6,57).
  • Numbers between −1 and +1 require a leading zero (0.02, not .02); exceptions are sporting performance averages (.430 batting average) and commonly used terms such as .22 caliber.
  • The digits after the decimal point can delimited into groups of three (e.g. 0.123456), especially in scientific contexts. Templates such as {{val}} do this automatically.

Units of measurement edit

Choice of units edit

Conversions edit

  • When parts of the English-speaking world use a different unit for a type of measurement than the one used in the article, generally provide a parenthetical conversion (e.g. 2,375 kilometres (1,476 mi)); Template:Convert can automatically handle many types of conversion.
  • In some specialized topics it is unnecessary to convert all occurrences of units such as yards in articles about American football, SI units and non-SI units accepted for use with SI in scientific articles, etc.; consider linking the units the first time they are used and/or giving a conversion factor in a footnote or parenthetical note.

Names and symbols edit

  • Generally use unit names in prose, and unit symbols in tables, mathematical formulas, and parenthetical notes.
  • Unit names are common nouns (even when named after a person) and are not capitalized except where common nouns normally are. For example, 101,325 pascals and 17th century, not 101,325 Pascals or 17th Century.
  • Unit symbols take no final dot or plural ending, are not italicized, and are preceded by numbers in figures, from which they are separated with non-breaking spaces ( ), e.g. 85 kg. The percent sign and the symbols of the degree, prime, and second of arc are unspaced (37%, 45°), but not the symbols of the degree Celsius and the degree Fahrenheit (20 °C).