# 9: Numbers

- Overview
- 9.1Overview and additional resources
- Numerals Versus Words
- General Principles
- 9.2Chicago’s general rule—zero through one hundred
- 9.3An alternative rule—zero through nine
- 9.4Hundreds, thousands, and hundred thousands
- 9.5Number beginning a sentence
- 9.6Ordinals
- 9.7Consistency and flexibility
- 9.8When numerals are always used
- Large Numbers
- 9.9Millions, billions, and so forth
- 9.10Powers of ten
- 9.11“Mega-,” “giga-,” “tera-,” and so forth
- 9.12Binary systems
- 9.13Use of “dex”
- Physical Quantities
- 9.14Physical quantities in general contexts
- 9.15Simple fractions
- 9.16Whole numbers plus fractions
- 9.17Fractions in mathematical contexts
- 9.18Numbers with abbreviations and symbols
- 9.19Units for repeated quantities
- Percentages and Decimal Fractions
- 9.20Percentages
- 9.21Decimal fractions and use of the zero
- Money
- 9.22Words versus monetary symbols and numerals
- 9.23Non-US currencies using the dollar symbol
- 9.24British currency
- 9.25Other currencies
- 9.26Large monetary amounts
- 9.27Currency with dates
- Numbered Divisions in Books and Other Documents
- 9.28Page numbers, chapter numbers, and so forth
- 9.29Volume, issue, and page numbers for periodicals
- 9.30Numbered divisions in legal instruments
- Dates
- 9.31The year used alone
- 9.32The year abbreviated
- 9.33Month and day
- 9.34Centuries
- 9.35Decades
- 9.36Eras
- 9.37All-numeral dates and other brief forms
- 9.38ISO style for dates
- Time of Day
- 9.39Numerals versus words for time of day
- 9.40Noon and midnight
- 9.41The twenty-four-hour system
- 9.42ISO style for time of day
- Numbers with Proper Names and Titles
- 9.43Numerals for monarchs, popes, and so forth
- 9.44Numerals with personal names
- 9.45Numbers for sequels
- 9.46Vehicle and vessel numbers
- 9.47Numbers for successive governments
- 9.48Numbered political and judicial divisions
- 9.49Numbered military units
- 9.50Numbered places of worship
- 9.51Unions and lodges
- Addresses and Thoroughfares
- 9.52Numbered highways
- 9.53Numbered streets
- 9.54Building and apartment numbers
- Plurals and Punctuation of Numbers
- 9.55Plural numbers
- 9.56Comma between digits
- 9.57The decimal marker
- 9.58Space between digits (SI number style)
- 9.59Telephone numbers
- 9.60Ratios
- 9.61Numbered lists and outline style
- Inclusive Numbers
- 9.62The en dash for inclusive numbers
- 9.63Abbreviating, or condensing, inclusive numbers
- 9.64Alternative systems for inclusive numbers
- 9.65Inclusive numbers with commas
- 9.66Inclusive years
- Roman Numerals
- 9.67Roman numerals—general principles
- 9.68The advent of subtrahends (back counters)
- 9.69Chicago’s preference for Arabic rather than Roman numerals