Claude for Excel Without the Made-Up Numbers
Use AI in Excel every day and send only numbers you've already checked.
You go at your own pace, with your Maestro beside you, 1:1, through the whole course: ask it anything, and it asks you questions too.
14 skills · 5 modules
Flash sale
$39
Back to $49 on November 15.
Comes with your Maestro, 1:1, for the whole course.
What will you be able to do?
Each box is a skill. The base is at the bottom, recognizing and explaining, and you work your way up to building something of your own and judging what works and why. Hover over a box to see what it builds on. Click it to see where I teach it and how your Maestro checks it.
- Evaluate
- Synthesize
- Analyze
- Apply
- Understand
Evaluate
Critique a complete AI answer about a workbook with the checks and a recount, and say what holds and what does not
Where I teach it: Your check, ready to send · Review the full summary the AI wrote
Builds on:
- Name what a percentage or average was divided by, and how blank cells changed it
- Find rows an AI's answer left out or counted twice: active filters, numbers stored as text, ranges that stop short and repeated rows
- Square an AI's total against an independent number you trust and explain the difference
- Test an AI's formula with a case whose answer you know, including a missing key, and spot when SI.ERROR hides the failure
Your Maestro asks you to judge when it fits and why and saves it as evidence when you do.
Choose how much to check an AI's Excel answer before using it, given what is at stake, and justify it
Where I teach it: Your check, ready to send · When is a quick check enough, and when isn't it?
Builds on:
- Critique a complete AI answer about a workbook with the checks and a recount, and say what holds and what does not
Your Maestro asks you to judge when it fits and why and saves it as evidence when you do.
Synthesize
Write a request that makes the AI give a formula, state its assumptions and propose a test you can run
Where I teach it: Ask for the formula, not the number · The prompt that asks for the formula, its assumptions and a test
Builds on:
- Tell a formula, a pasted value and an AI function result apart, and say which one you can check
- Test an AI's formula with a case whose answer you know, including a missing key, and spot when SI.ERROR hides the failure
Your Maestro asks you to build something of your own with it and saves it as evidence when you do.
Build a reusable check sheet for any workbook: row counts, a total squared against a known source, and flags for text and repeats
Where I teach it: Your check, ready to send · Your check sheet for any workbook
Builds on:
- Square an AI's total against an independent number you trust and explain the difference
- Find rows an AI's answer left out or counted twice: active filters, numbers stored as text, ranges that stop short and repeated rows
Your Maestro asks you to build something of your own with it and saves it as evidence when you do.
Analyze
Name what a percentage or average was divided by, and how blank cells changed it
Where I teach it: When AI analyzes the whole sheet · What did it divide by? Percentages and blank cells
Builds on:
- Recount at the grain the question asks for, such as distinct tickets instead of rows, with Excel functions or a pivot table
Your Maestro asks you to break a problem down with it and saves it as evidence when you do.
Find rows an AI's answer left out or counted twice: active filters, numbers stored as text, ranges that stop short and repeated rows
Where I teach it: When AI analyzes the whole sheet · What got left out? Filters, numbers stored as text and repeated rows
Builds on:
- Square an AI's total against an independent number you trust and explain the difference
- Recompute a few rows spread across the table with a check column and compare them with the AI's result
Your Maestro asks you to break a problem down with it and saves it as evidence when you do.
Apply
Make an AI's formula run in your Excel: function names in Spanish or English and the argument separator
Where I teach it: Ask for the formula, not the number · How to use XLOOKUP, and why the AI's formula breaks in your Excel
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Recompute a few rows spread across the table with a check column and compare them with the AI's result
Where I teach it: Three checks inside Excel · Work rows by hand: the check column
Builds on:
- Read an AI's Excel formula argument by argument and say what each part does and which cells it touches
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Test an AI's formula with a case whose answer you know, including a missing key, and spot when SI.ERROR hides the failure
Where I teach it: Three checks inside Excel · Make it fail: the SKU nobody added, and the 0 that hides it
Builds on:
- Read an AI's Excel formula argument by argument and say what each part does and which cells it touches
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Square an AI's total against an independent number you trust and explain the difference
Where I teach it: Three checks inside Excel · Reconcile to the register closeout
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Recount at the grain the question asks for, such as distinct tickets instead of rows, with Excel functions or a pivot table
Where I teach it: When AI analyzes the whole sheet · What is a row? The average ticket that was averaged by line
Builds on:
- Recompute a few rows spread across the table with a check column and compare them with the AI's result
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Understand
Describe what Copilot in Excel, ChatGPT and Claude do with your workbook: what they read, whether they work on a copy or in place, and what they hand back
Where I teach it: What AI does with your workbook · What does Claude for Excel do to your workbook?
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Tell a formula, a pasted value and an AI function result apart, and say which one you can check
Where I teach it: What AI does with your workbook · Formula, pasted value or =COPILOT()? Read what the AI left in your cells
Builds on:
- Describe what Copilot in Excel, ChatGPT and Claude do with your workbook: what they read, whether they work on a copy or in place, and what they hand back
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Read an AI's Excel formula argument by argument and say what each part does and which cells it touches
Where I teach it: Ask for the formula, not the number · Read the AI's formula one argument at a time
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Who is this course for?
For anyone who already asks Claude, Copilot or ChatGPT for Excel formulas or analysis and has to hand that number to someone: sales, inventory, budgets, the weekly report. If you can write a simple formula like SUM and filter a table, you're ready. No coding.
Ask your Maestro
Your Maestro is an AI that knows each course, page by page. Try it here free, in the free course "Your AI and Your Data: Don't Let It Make Up the Number".
You: Where do I start?
Your Maestro: From what you already know. Tell me what you've done with data, and I'll start this page from there.
Asking about: Answers from the page "Count or rate? How to compare groups of different sizes"
Only this browser keeps what you ask here. How it works
What we'll cover
What AI does with your workbook
- How to use AI in Excel without trusting a made-up numberreference
- What does Claude for Excel do to your workbook?
- How to use Copilot in Excel, and what ChatGPT does with your file
- Formula, pasted value or =COPILOT()? Read what the AI left in your cells
Ask for the formula, not the number
- How to use XLOOKUP, and why the AI's formula breaks in your Excel
- Read the AI's formula one argument at a time
- The prompt that asks for the formula, its assumptions and a test
Three checks inside Excel
- Work rows by hand: the check column
- Make it fail: the SKU nobody added, and the 0 that hides it
- Reconcile to the register closeout
When AI analyzes the whole sheet
- What is a row? The average ticket that was averaged by line
- What did it divide by? Percentages and blank cells
- What got left out? Filters, numbers stored as text and repeated rows
Your check, ready to send
- Review the full summary the AI wrote
- Your check sheet for any workbook
- When is a quick check enough, and when isn't it?
How long does it take?
1.5 to 2 hours
A guide: you go at your own pace, and the course waits where you left off.
Common questions
- What is Claude for Excel, and do I need it for this course?
- Claude for Excel is Anthropic's add-in that puts Claude in a sidebar inside Excel, on Claude's Pro, Max, Team and Enterprise plans. The course leads with it because it reads and edits your open workbook, which changes what you check first. You don't need it: every check works the same with Copilot in Excel, ChatGPT or any assistant, and the first module shows what each one does to your file.
- How do I use AI in Excel without getting a made-up number?
- Ask for a formula instead of a number, because a formula can be read and tested. Then run three checks: work a few rows by hand, try a case that should fail, and reconcile the total to a number you trust, like the register closeout. The course practices all three with Claude, Copilot and ChatGPT on the same workbook.
- Can ChatGPT analyze my Excel file?
- Yes, on a copy. When you upload a workbook, ChatGPT loads its own copy and usually runs a short program on it. Your file doesn't change, and the first thing to ask is how many rows it read and whether it skipped any. Module 1 shows the difference between that and an add-in that works inside your open workbook.
- Why doesn't the AI's XLOOKUP work in my Excel?
- Usually one of three things: your Excel is 2019 or older and has no XLOOKUP, the formula came with curly quotes from a chat or document, or it was written with semicolons for a European Excel. Module 2 fixes all three and then teaches you to read the formula one argument at a time before you trust it.
- Do I need to code or know a lot of Excel?
- No. Everything happens in Excel, with no code. If you can write a simple formula like SUM and filter a table, you're ready. Your Maestro helps you on every page.
- Does it work with Google Sheets?
- Yes. The checks are the same, and the functions the course uses, including XLOOKUP, exist in Sheets under the same names. Where a menu is different, the page says so.
- Do I have to upload files from work?
- No. You practice on a workbook of made-up data from a fictional garden supply company. Before you give any assistant a file from work, check what your company allows. The course teaches you to check the answer; it never asks for your files.
- How long is it, and what's included?
- Five modules and 16 pages, an hour and a half to two hours. You get the practice workbook, sheets right on the page that tell you when your formula is right, your Maestro on every page, and a check sheet you can copy into any workbook.
How do I check what AI does? I teach it in Your AI and Your Data: Don't Let It Make Up the Number and Check what AI gives you in three steps.
What you get
- 5 modules and 16 pages, open whenever you want them.
Your Maestro for the whole course, who always knows which page you're on: you open it from there.
It works from this course's skills, the ones above.
Ask it how you're doing, and it tells you what you've already shown and what comes next.
Words you'll meet
In the lessons, tap one to see what it means, or ask your Maestro about it.
Who's teaching you
Sergio Sánchez
I'm Sergio, chekos online. I'm a data architect, and I've spent more than ten years working with data in the Bay Area, mostly at mission-driven organizations: policy research first, then education, and now early childhood services. I grew up in Tijuana. In 2018 I started tacosdedatos to share what I was learning, and since then it's been a blog, a podcast, courses, guides, and a community. These days I spend a lot of my time building with AI agents and writing about how I organize my work around them. I share what I've learned; you take what's useful and make it yours.
See you in the course
Claude for Excel Without the Made-Up Numbers