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8. Numbers

Numerals

This is what you call numbers that are not written out, but shown as their numeric symbol (see also).

1, 2, 3, 4, 5

Cardinal Numbers

regular numbers that count and show quantity.

1, 2, 3, one, two, three

Ordinal Numbers

ordered numbers that have a suffix (see also).

1st, 2nd, 3rd, first, second, third

Spelling (one, two, three) vs Numerals (1, 2, 3)

The golden rule for numbers:

Spell out all simple numbers (one, fourteen, twelve hundred). Use numerals for all complex numbers (229, 617).

Simple numbers can be written out without needing or wanting to use an "and," while complex numbers would need or want an "and" in order to be written out. 

Exceptions to the golden rule:

In informal speech, online materials, or number-focused materials (ex: a scientific paper) always favor numerals for better visual readability and to emphasize the numbers in number-focused materials. 

It is best to show numbers in text the way you would encounter them in the world. For example, "hotel room 300" would always be encountered as a numeral in the real world so we keep it a numeral.

Numbers in Dialogue

Numbers in dialogue are almost always spelled out to show how they are being said/spoken aloud. 

Hyphenating Numbers

Hyphenate all numbers that have two words, unless they are a round number that is higher than ninety-nine (see also).

twenty-two vs one hundred

Currency

Use the dollar sign symbol before the numeral amount when talking about US dollars. Using the word "dollars" is then unnecessary.

NO: $100 dollars, 100 dollars, one hundred dollars YES: $100

Dates

Use the following format for dates: month day, year.

NO: the 14th of May in 2005 YES: May 14, 2005

Use superscripts for dates when only the month and date is present. 

NO: May 14th, 2024 YES: May 14th

Phone Numbers

Place parentheses around the first set of numbers. Use a space between the first and second set of numbers. Use a hyphen between the second and third set of numbers. OR use a hyphen between each set of numbers in the phone number.

NO: 800 555-5555, 8005555555 YES: (800) 555-5555, 800-555-5555

Time

Don't capitalize the word "hours" in "24 hours."

Write times in numeral format with AM and PM in all caps with no periods. Include one space between the time and the AM or PM that goes with it. 

NO: 24 Hours, 11:30 am, 2:30 a.m., 3:00am, 9 PM  YES: 24 hours, 11:30 AM  YES: The coffee shop is usually open from 9:00 AM to 8:00 PM.

Numbered Lists

A numbered list uses the numeral number, a period, and an indentation.  1. item one 2. item two 3. item three

A numbered list in running text uses a parentheses after the number with a colon preceding the numbered series. There are a few other ways to clearly outline a numbered list in running text but this one is my preferred practice.

NO: The main things you need to remember are 1 item one 2 item two and 3 item three. YES: The main things you need to remember: 1) item one, 2) item two, and 3) item three.