Spell out cardinal numbers from zero through nine and all ordinal numbers: one, two, first, second, seventy-ninth
Use numerals for all numbers 10 and higher: 11, 22, 1030

Exceptions
Use numerals for all numbers:

- used in measurements or dimensions, time, dates (6 degrees, 8.5 by 11 inches, 6 weeks)
- used with other numerals in the same sentence. (Your manual may have 5, 10 or 20 pages.)
- for large round numbers above 1 million: 7 trillion

Use 24-hour clock with minutes: 14:25 UTC

Use month name in dates: 12 June 2009 or June 12, 2009

Use numerals for numbered sections in documents: Chapter 1, Part 7

For decimal fractions less than one, use a leading zero: 0.5 mm