Why it helps
You know what you want the spreadsheet to do: "add up everything for this customer", "take the GST out", "show the date 20 days from now". Turning that into a formula is the bit that sends you down a rabbit hole of forums and videos.
AI is very good at this. Describe your columns and what you want in plain English, and it writes the formula and explains it. Ask for the explanation every time, and you'll find you need it less and less.
The prompt
Copy it, swap the bits in [square brackets], and paste it into ChatGPT, Claude, Gemini or Copilot.
I'm using [Excel / Google Sheets] in New Zealand. Write me a formula and explain it simply, in NZ English. My sheet: [describe your columns, e.g. column A is date, column B is customer name, column C is amount incl GST. Data is in rows 2 to 200.] What I want: [describe it in plain words, e.g. the total for the customer named in cell F1] Please: 1. Give me the exact formula and which cell to put it in. 2. Explain what each part does, in one or two lines. 3. Tell me if it won't work in older versions of Excel, and give me an alternative if so. 4. Tell me one way to check it's giving the right answer. Don't assume columns or data I haven't described. If you need more information, ask me.
Then keep chatting
It's giving me #N/A. Here's the formula and what's in the cells: [paste]. What's wrong?
Now do the same but only for dates in October 2026.
Round the answer to 2 decimal places.
Explain this formula someone else wrote: [paste formula]
Step by step
- Look at your sheet and note which column holds what, and which rows your data is in.
- Write what you want in plain words, the way you'd explain it to a mate.
- Paste the prompt with your description. Copy the formula into the cell it suggests.
- Check the answer against a couple of rows you can work out in your head or on a calculator.
- If it errors, paste the error and the formula back in and ask what's wrong.
Worked example
Example details are made up. Your results will vary, so always read and check before you use them.
Watch out for
- Check the answer on a few rows yourself. A formula can look fine and still point at the wrong column or miss the last rows.
- AI sometimes mixes up Excel and Google Sheets, or uses functions your version doesn't have. Tell it exactly which one you use.
- Privacy: describe your columns instead of pasting real data. If you need to show an example, use made-up names and amounts. Don't paste customer details, bank account numbers or staff pay.
- For GST, the formula maths is simple, but what's GST-inclusive and what's claimable isn't a spreadsheet question. Check ird.govt.nz or your accountant.
Go further
Keep a "Formulas" tab in your spreadsheet with the ones you use often and a note on what each does. When you're ready for more, ask AI to teach you step by step with the [learn anything tutor](/use-cases/learn-anything-tutor), or build a [simple cashflow forecast](/use-cases/simple-cashflow-forecast) using what you've learned.
