---
source: https://iinventedlight.com/library/notes/plain-explain-numbers-do-the-math.md
title: "Explain what each number means and do the math for the reader"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; original synthesis in our own words"
license_family: usgov
attribution: "Summary by iinventedlight (AI-assisted). Sources: Centers for Disease Control and Prevention (CDC), CDC Clear Communication Index: User Guide, US government work, public domain; U.S. Web Design System (GSA), Data visualizations, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-09
status: published
checked_on: 2026-11-09
as_of: 2026-11-09
confidence: medium
untested: "Editorial checklist only; not tested with readers. Sources fetched and evidence checked."
category: coverage-gaps
topic_area: "write-comm"
tags: [plain-language, numbers, context, write-comm]
client: Librarian
sources:
  - id: S1
    title: "CDC Clear Communication Index: User Guide"
    publisher: Centers for Disease Control and Prevention (CDC)
    url: https://www.cdc.gov/ccindex/pdf/clear-communication-user-guide.pdf
    accessed: 2026-11-09
    license: "US government work, public domain"
  - id: S2
    title: "Data visualizations"
    publisher: U.S. Web Design System (GSA)
    url: https://designsystem.digital.gov/components/data-visualizations/
    accessed: 2026-11-09
    license: "US government work, public domain"
---
# Explain what each number means and do the math for the reader

**Answer:** To help people make sense of numbers, present them in context and explain what they mean. Do the math rather than expect the audience to calculate.

## Explain (CDC Clear Communication Index, item 16)

- Provide reasons why the numbers are important to the main message and the audience's understanding.
- As with words, numbers can mean different things to different people.
- Ask: is the number high or low for this type of issue, or higher or lower than expected?
- Avoid qualitative descriptors such as high and low or large and small by themselves; also give the number and explain the meaning.

## Calculate (item 17)

- Do the math rather than expect the audience to calculate; provide calculations and conversions.
- Keep the denominators constant: use the same denominator throughout so audiences don't have to calculate.

## For charts

Get to the point: clearly state the author's intended message as text, so the audience is not left guessing as to the conclusion.

## See also

- [plain-numbers-readers-use](https://iinventedlight.com/library/notes/plain-numbers-readers-use/)
- [plain-chart-states-its-message](https://iinventedlight.com/library/notes/plain-chart-states-its-message/)

## Claims

- id: C1
  claim: Explain what numbers mean.
  source: S1
  evidence: "Does the material always explain what the numbers mean?"

- id: C2
  claim: Present numbers in context.
  source: S1
  evidence: "To help people make sense of numbers, present them in context."

- id: C3
  claim: Do the math for the audience.
  source: S1
  evidence: "Be sure to do the math rather than expect the audience to calculate."

- id: C4
  claim: USWDS: state the intended message as text.
  source: S2
  evidence: "Clearly state the author's intended message as text."

## Sources

- [S1] CDC Clear Communication Index: User Guide. Centers for Disease Control and Prevention (CDC). https://www.cdc.gov/ccindex/pdf/clear-communication-user-guide.pdf . License: US government work, public domain. Accessed 2026-11-09.

- [S2] Data visualizations. U.S. Web Design System (GSA). https://designsystem.digital.gov/components/data-visualizations/ . License: US government work, public domain. Accessed 2026-11-09.


License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources: US federal government works (GSA, GPO, SEC, CDC), public domain in the United States; third-party quotations inside those works were not used. Text was condensed and changed from the originals.

---

Agents: [/agents.md](/agents.md) | [/.well-known/agent-library.json](/.well-known/agent-library.json).