A focused workflow for formulas: how to ask, how to debug with it, and how to make inherited formulas readable again.
Formula work is where ChatGPT pays off fastest, because a formula is short, testable and easy to describe precisely.
Writing a new formula
State the Excel version, the table or ranges with headers, the rule in business language, and the tie-breakers. Ambiguity is what produces a wrong formula, not the model.
Excel 365, Table tOrders.
Columns: OrderDate, Customer, Amount, Status.
Return the largest Amount per Customer where Status = "Delivered",
as a spill range with Customer in the first column.Debugging an error
| Error | Usual cause | What to ask |
|---|---|---|
| #N/A | Lookup value missing or type mismatch | "Which argument can produce #N/A here?" |
| #VALUE! | Text where a number is expected | "Which argument expects a number?" |
| #REF! | Deleted row or column | "Rewrite this so deleting a column cannot break it" |
| #SPILL! | Blocked spill range | "Why would this dynamic array be blocked?" |
Making inherited formulas readable
Paste a 300-character nested IF and ask for a LET version with named steps plus a one-line explanation of each. You end up with a formula the next person can maintain, which matters more than cleverness.
Always test on known data
Run any generated formula on ten rows where you already know the answer before applying it to fifty thousand. This one habit prevents almost every AI-assisted formula mistake we see in training.
Frequently asked questions
- Does ChatGPT know the newest Excel functions?
- Usually, but always confirm the function exists in your version. If a suggested function is unavailable, ask for an alternative using only classic functions.
Learn this properly, with a trainer
Advanced Excel with Raj Singh — classroom in Vasai or live online. Batch timings are confirmed when you enquire.
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