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Explain an Excel formula step by step

Understand what a formula calculates, its dependencies, and where it can fail

3 min setupTested with:ChatGPTReviewed: 2026-08-28

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FormulaWorkbook contextSample values

Your prompt

Unfilled fields remain visible as placeholders, so you can still copy and edit the prompt

Explain this Excel formula without changing it:
[formula]

Workbook context:
[context]

Sample values:
[sample]

Return:
- A one-sentence description of the final result
- A nested breakdown evaluated from the innermost operation outward
- A worked calculation using the sample values
- Every cell, range, table, or named-range dependency
- The meaning of absolute and relative references
- Likely failure modes involving blanks, text, errors, dates, or missing matches
- Two questions to confirm with the workbook owner

Do not claim the formula is correct without comparing its behavior with the stated intent.

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From input to outcome

A worked example

See how concrete context turns this recipe into a usable result

Actual input

Formula: =IFERROR(ROUND((D2-C2)/C2,2),"Check input")
Workbook context: C is last month's revenue, D is this month's revenue. The cell should show the decimal growth rate rounded to two places.
Sample values: C2=8000; D2=9200.

Example output

Result: The formula calculates month-over-month revenue growth as a decimal, rounds it to two places, and replaces any calculation error with “Check input.”

Inside out: D2-C2 finds the revenue change. Dividing that change by C2 expresses it relative to last month. ROUND(...,2) keeps two decimal places. IFERROR catches every Excel error from the calculation.

Worked example: 9,200 − 8,000 = 1,200; 1,200 ÷ 8,000 = 0.15; rounding gives 0.15, which displays as 15% only if the cell uses percentage formatting.

Dependencies: C2 and D2 only. Both are relative references, so copying the formula down changes them to C3/D3, then C4/D4.

Failure modes: C2 equal to zero triggers the fallback; numeric text may behave inconsistently; blanks can be treated as zero; IFERROR hides the difference between a zero denominator and corrupted input. Confirm whether zero prior revenue should show “new” rather than an error, and whether blank current revenue means zero or missing data.

Why this works

1
Working from the inside out makes nested formulas easier to audit.
2
A real sample distinguishes a plausible explanation from the formula's actual behavior.