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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
• 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.

@misc{iil_note_b4dyabta,
  author = {{iinventedlight}},
  title = {{Explain what each number means and do the math for the reader}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-09},
  url = {https://iinventedlight.com/library/notes/plain-explain-numbers-do-the-math/},
  note = {Permanent ID iil:note:b4dyabta. License: CC-BY-4.0.},
}

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