Inherited a mystery spreadsheet? This AI prompt decodes every tab and formula

October 20, 2026

By Katie Knauf

I can feel my shoulders rise when someone sends a 14-tab Excel file named FINAL_v7_REAL.xlsx. 

Half the headers look like airport codes, formulas disappear into hidden columns and the person who built it has left the company, the state, possibly society. From the looks of the formulas, the great unraveling started sometime around Q3 2019. 

You could spend an afternoon clicking tabs and hoping the spreadsheet eventually introduces itself. Or you can make AI interrogate the thing.

Start with a copy, never the only version. Remove customer names, employee details, financial account numbers and anything confidential before uploading. If company policy blocks uploads, paste the column headers, a few typical rows and the ugliest formulas into your approved AI tool.

Then paste this into your favorite chatbot: 

Act as a senior data analyst inheriting this spreadsheet with no documentation.

Explain the spreadsheet’s likely business purpose in plain English. Describe what each tab appears to track, how the tabs connect and which columns seem most important.

Audit the formulas. Flag broken references, inconsistent ranges, hard-coded numbers, duplicated logic and assumptions that may fail when new rows are added. Don’t claim certainty when context is missing. List the questions I should ask the previous owner or stakeholders.

Then write a one-page “How This Works” document covering:

• What this spreadsheet is for  

• Where the source data comes from  

• How to update it safely  

• Which outputs people should trust  

• Which formulas or tabs need human review  

• The five most important insights currently visible

End with a short verification checklist before anyone uses this file for a decision.

AI can explain a formula. It can’t know that Finance stopped using Tab 6 nine months ago while Sales still treats it like scripture. Check totals against a trusted report, test suspicious formulas and ask the people who use the output whether the narrative matches reality.

Your move this week: Open the spreadsheet you dread most and produce the one-page note. Then send it to the people who rely on the file and ask, “What’s wrong, missing or outdated?”

You’ve just turned spreadsheet archaeology into visible leadership.