Numbers and Organization

Numbers, lists, and headings give a reader useful landmarks. Present them so the relationships are easy to see and the details are easy to find.

8.1Headings and Titles

Use descriptive headings and a logical hierarchy. Keep headings at the same level parallel in structure. Apply heading styles rather than manually changing size and weight. Follow the capitalization conventions chosen for the document. Avoid skipping heading levels.

8.2Numbers and Symbols

8.2.1Numerals Vs. Words

In ordinary prose, spell out one through nine and use numerals for 10 and above. Use numerals with units of measurement and where comparison calls for them.

Example: Bring three apples and 12 napkins.

Example: Cut a strip 3 cm wide.

Keep the form consistent within a closely related series.

8.2.2Number Ranges

Use an en dash for a compact range, or write the range in words. Pair from with to and between with and.

Compact: Read pages 4–6.

In words: The garden is open from three to four.

In words: Bring between four and six cups.

Include enough context to tell readers what the endpoints mean.

8.2.3Large Numbers and Decimals

Use the grouping and decimal convention familiar to your readers. A comma groups thousands in American and British English, while other places may use a space or a different grouping pattern.

Comma grouping: 1,550

Indian grouping: 1,00,000

Decimal point: 3.14

Keep only as many decimal places as the meaning needs. In international writing, explain an unfamiliar convention rather than assuming every reader uses the same one.

8.2.4Ordinals

In ordinary prose, spell out first through ninth and use numerals from 10th onward. Use numerals earlier when a label, comparison, or familiar convention makes them clearer.

Example: Her first visit was on her 12th birthday.

Keep ordinal endings on the baseline in everyday text. A date doesn’t usually need one: April 3 is enough.

8.2.5Currency

Use a currency symbol when readers will know which currency you mean. For an international audience, add a clear currency code or name.

Local context: The notebook costs $30.

International context: The notebook costs USD 30.

8.2.6Units of Measure

Use numerals with unit symbols and follow the spacing convention for the unit. Most symbols take a space after the number. A nonbreaking space keeps the value and unit together.

Length: 3 cm

Mass: 5 kg

Temperature in SI style: 20 °C

Plane-angle symbols are an exception: 90° has no space. Give a conversion when it helps readers use the information.

8.2.7Arithmetic

Mathematical notation can make a calculation easier to follow. Use the multiplication sign (×), division sign (÷), and minus sign (−) when the format supports them.

Addition: 3 + 2 = 5

Multiplication: 3 × 2 = 6

Division: 6 ÷ 2 = 3

In a sentence, plus or divided by may feel more natural. For code, use the operators the language expects. On a Mac, Character Viewer is one way to find mathematical symbols.

8.2.8Symbols

Define all specialized symbols used in technical or mathematical contexts to avoid confusion.

• Avoid using unnecessary symbols.

8.3Lists and Procedures

Lists make related information easier to scan. Use bullets when order does not matter and numbers when readers need to follow a sequence. Keep the wording, capitalization, and punctuation consistent.

8.3.1Bullets and Unordered Lists

Use bullets for related items when order doesn’t matter. Give the items parallel wording.

• Reading by the window
• Walking along the river
• Cooking with friends

Use a period after a complete sentence. Leave short fragments and individual items without end punctuation. Avoid mixing fragments and full sentences in one list.

8.3.2Ordered Lists

Number steps when the order matters. Begin with an action and include the information needed to complete it.

1. Fill the kettle with water.
2. Boil the water.
3. Pour it over the tea and let it steep.

Use sentence case and periods for complete instructions. Keep the sequence logical, and use substeps only when they make the task easier to follow.

8.3.3Vertical Lists With Lead-Ins

Introduce a list with a lead-in that fits its grammar. Use a colon after a complete introductory statement.

Example with fragments:

Pack the following:

• A blanket
• A water bottle
• A book

Example with complete sentences

Before you leave:

• Check the weather.
• Lock the door.
• Tell someone when you expect to return.

Use a sentence instead if the list adds unnecessary complexity.

8.3.4Procedures and Instructions

Make instructions clear, concise, and actionable. Use numbered steps when order matters, and explain unfamiliar actions before asking the reader to perform them.

• Begin each step with an action verb.
• Use second person and present tense.
• Break a complex task into manageable steps.
• Include prerequisites and consequences where readers need them.
• If an instruction refers to an app or website, match its actual labels.

Example procedure:

1. Fold the paper in half.
2. Write the guest’s name on the front.
3. Place the card beside their seat.

8.4Reference and Navigation

A useful link, a clear contents page, or a well-placed note can save readers from losing their place. Make the destination clear and keep extra detail close enough to find.

8.4.1Tables of Contents

When creating longer documents or documents with several sections, consider adding a table of contents.

• Use a hierarchical structure that mirrors section headings (e.g., H1, H2, H3) or section numbers (e.g., 1, 1.1, 1.1.1).
• Avoid including non-essential headings.
• Indent subsections for visual clarity.
• Link each item to its corresponding section using anchor links. Many table of contents generators do this automatically and will update as the document changes.
• Keep the contents and headings in step when you revise the piece.

8.4.2Hyperlinks and URLs

Link words that describe the destination. A reader should have a reasonable idea of what will open before selecting the link.

Vague: Click here

Clearer: Download the picnic checklist

Underline text links or give them another cue beyond color. Check that each link opens the intended page. A visible URL can be useful in print or when the address itself matters.

8.4.3Text Links

Choose a short, descriptive phrase for a text link. Include enough context to distinguish it from nearby links, and avoid sending identical wording to different places.

Example link text: Read the bread recipe

A whole sentence can be a link if it reads naturally. Keep the linked area easy to recognize.

8.4.4Anchor Links

Use anchor links to help readers reach a specific part of a long webpage. Link to a meaningful heading, and make the destination clear from the link text.

Use readable anchor names, such as #packing-list. Check that the link reaches the intended section.

8.4.5Footnotes

A footnote lets you add a source or a useful aside without breaking the main thought. Keep essential information in the main text.

Text: The walk follows the old railway line.¹

Note: ¹ The line closed to passenger trains in 1968.

Use a consistent numbering and placement convention. Keep notes readable, and make digital markers link to their notes where possible.

The example above is fictional.

8.5References and Citations

Give readers a way to find the sources behind a claim, quotation, or borrowed idea. A descriptive link often works for an online article; an essay or academic piece may call for a formal citation style.

Choose a citation system that fits the piece, such as APA, MLA, or Chicago, and use it consistently. Follow a publication’s citation convention when writing for it.