How AI Analyses Your Spreadsheet

How can ChatGPT or Claude analyze an Excel sheet with 10,000 rows when all they do is predict the next word?

Here's the secret. They don't read every row. They write code, and the code does the work.

Where does your spreadsheet go first?

It goes into a temporary virtual computer, which is a computer in the cloud where programs can run on your file. The AI then writes a little code to check the sheet names, column headings and a few sample rows, so it understands how your data is organized without reading all 10,000 rows.

How does the AI write the code for your analysis?

The same way it writes everything else, by predicting the next word, and writing code is something AI does very well. Say you ask for last month's total sales, and the AI writes Python code, a set of instructions for the computer, that picks the right dates and adds up the amounts.

So who actually does the maths?

The virtual computer runs that code, just like a program on your own laptop, and goes through every row. The result then goes back to the AI, which predicts the next word again to turn it into explanations, summaries, tables or charts.

Then why can the answer still be wrong?

The code does exactly what the AI told it to do. If your Sales column actually holds sales targets and the AI treats them as real sales, it adds every row perfectly and still gives you the wrong answer.

How can you trust the result?

Give the AI clean data with clear, accurate headers, and ask what it assumed about each column. Then check one number you already know, because if that one is right, the rest is far more likely to be right too.

What to remember

AI writes code to work through your spreadsheet, and a computer runs that code on every row to do the maths. Clear headers, a quick look at its assumptions and one number you already know help you get answers you can trust.