At the beginning of a sentence: Twenty-five people were part of
the development team.
If the number is fewer than 10: Of the seven systems, the administrator
backed up six daily. This rule applies unless the number precedes
a unit of measure.
When depicting approximate numerals in hundreds or thousands:
The managed forest contained about six thousand trees.
Use numerals:
For numbers 10 or greater.
For approximate numbers above 999,999, use the numeral
followed by x`“million” or the appropriate word instead
of all the zeros: The solar system is estimated to be about 4.5 billion
years old.
For specific round numbers, such as 34,000 and 200,000,
use the full numeral, including the zeros. Don't use “thousand”:
Custom views display only the most recent 200,000 rows from the filtered
data set.
For units of measure, including angles, areas, lengths, money,
percentages, time (including years, months, weeks, and days), and
volume. This applies
even if the number is under 10, as in 5 inches.
In a group of two or more numbers when at least one of the numbers
is 10 or more: The program reports 17 errors, 9 major and 8 minor.
To identify an object by number: bits 0 and 1.
For decimals: 3.4, 16.7.
For fractions in a unit of measure or in a mixed number: (1/2-inch
measure, 4 1/2 times as much.
If a number precedes an abbreviation or symbol: 14%, 30+ mpg.
Don't use abbreviations like K for
thousand; or M or MM for million.
If two numbers are adjacent, spell out one: four 8-character form entries; thirty-two 8-bit bytes.
To form the plural of a numeral, add s but no apostrophe: Type three 2s.
When a measurement is used as an adjective, use
a hyphen to connect the number to the measurement, as in 10-point
type. Otherwise, don't use a hyphen.
Hyphenate a fraction written as words: Three-fifths, Four and one half.
Hyphenate a two-element number under 100: Sixty-three, twenty-one.
Don't use st, d, and th after
numerals in dates to indicate ordinals: April 15, not April 15th.
Don't use both a numeral and a word for the same number in a sentence,
as in six (6). One or the other is enough: The document is
in six files.
Always spell out the word number in text. Where space is
tight, as in tables, it’s okay to use the abbreviation no. instead.
For numbers with four or more digits,
use commas between groups of three digits, for example, 1,000 emails
per user.
In UI text, some features, such as dashboards and feeds, do include abbreviations of large
numbers (in the thousands or bigger).
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