Proofreading numbers in business documents is harder than proofreading words. Your brain reads text in chunks and fills gaps from context, but it treats numbers as individual characters. It's also less likely to flag a wrong one as suspicious. A misspelled word looks wrong. A transposed digit looks exactly like a correct number.
That asymmetry matters. A proposal quoting £14,500 when the approved figure is £41,500 is not a typo your reader will charitably overlook. Neither is a delivery date that skips a month, a percentage that adds up to 101%, or a table where the totals don't match the rows above them. These are the mistakes that survive spell-check, pass a quick read, and arrive in someone's inbox fully intact.
Why numbers demand a separate pass
Most writers proofread once, reading the document as a whole. That method catches a lot of text errors. It catches very few numerical ones. The problem is attention: when you're reading for sense and flow, your eye skips across figures without verifying them. You see "Q3 revenue of $2.4 million" and your brain confirms it makes narrative sense. It doesn't check whether the table on the next page says $2.1 million.
Numbers also tend to cluster in the places readers trust most: executive summaries, financial tables, contract terms, timelines. A reader who skims the body text will often stop and read a table carefully. If that table is wrong, there's nowhere to hide.
Give numbers their own pass. Read through the document once for language and structure, then go back specifically for figures. It takes ten minutes on most documents. It's the same logic behind a five-step proofreading checklist: separating categories of error stops them from masking each other.
What to check, specifically
Not all numerical errors are equal. These are the categories that cause the most damage in professional documents.
Totals and cross-references
Any figure that is the sum of other figures needs to be verified against those components. Add the rows yourself, on a calculator, not in your head. Then check whether the same total appears anywhere else in the document: in the executive summary, in the body text, in a cover letter. If a number appears in three places and you correct it in one, the other two become new errors.
Dates and timeframes
Dates are the category where transposition errors hide most effectively. 14 March and 4 March look similar at a glance. A timeline showing a two-week gap that is actually four days will not be caught by reading the dates in sequence. Check the arithmetic, not just the figures. Also watch for internal consistency: if the document says "the project runs from 5 May to 30 June" and elsewhere mentions "the eight-week delivery window," both can't be right.
Percentages
Percentages must add up to 100% if they're describing parts of a whole. They also need to match their source. If you write "costs fell by 12%" and the table shows a reduction from $80,000 to $71,200, verify that the arithmetic agrees. Also check whether you've written the percent sign consistently. A document that uses "%" in some places and "per cent" in others looks unfinished.
Decimal places and currency
Decide early whether figures are presented to zero, one, or two decimal places, and hold to it. A table mixing "$1,200.00" with "$1.2K" and "$950" is not just inconsistent: it makes comparison harder and signals carelessness. For currency, confirm that the symbol and the amount match throughout. In international documents, an unattributed "$" is genuinely ambiguous.
Version numbers and reference codes
Contract reference numbers, policy version numbers, and document identifiers look identical to the eye when they differ by a single digit. Verify these by reading them character by character, ideally against the source document. It's slow. It's also the only method that works.
Practical techniques that actually help
Reading aloud works well for text but poorly for numbers. It's hard to catch a transposition by speaking the digits, because your mouth produces what your eye expects. Instead, try these approaches.
Use a ruler or blank sheet of paper to isolate each row of a table as you verify it. This forces your eye to look at the figures, not the surrounding words. For critical figures, read the number character by character from right to left. That breaks the pattern your brain expects and makes transpositions visible.
For any document with a financial table, print the source data (from the spreadsheet or the brief) and check figures against the printed source, not from memory. This is the step most writers skip because it takes longer. It's also the step that catches the most errors.
If the document includes figures that were calculated elsewhere, recalculate them. Don't trust that the spreadsheet is correct just because it came from finance. Spreadsheets have formula errors. Models get updated and summaries don't. The proofreader who checks the arithmetic is the last line of defence before the reader becomes the error-finder.
One more thing: spell-check misses numerical errors entirely. A spell-checker has no concept of what a correct figure should be. It will flag "recieve" but it won't flag a contract value that's off by $10,000. No tool substitutes for systematic human verification of numerical content.
Building a checklist for numerical proofreading
Before you send any document containing numbers, run through these checks in order.
- All totals verified by independent calculation, not read-back
- Same figure cross-referenced consistently wherever it appears
- All dates verified for accuracy and internal consistency
- Percentages add to 100% where applicable
- Decimal places and currency symbols consistent throughout
- Reference codes and identifiers verified character by character
- Figures in body text match the supporting tables
This checklist takes less time than it looks. Most documents have fewer than a dozen distinct figures that need verification. The investment is five minutes. The cost of skipping it can be much larger.
A note on automated tools
Grammar checkers and free writing tools don't verify numerical accuracy. They check that "forty-five" is hyphenated correctly. They don't check whether the underlying figure is forty-five or fifty-four. Tools like Grammarly will flag grammatical inconsistencies around numbers (writing out "one" through "nine" but using "10" as a numeral), which is useful for consistency. But the arithmetic and the accuracy remain entirely the writer's responsibility.
Use tools for what they do well. Reserve the numerical pass for yourself, on paper, with a calculator, before the document goes anywhere.