Most people open ChatGPT, drop in an Excel file, and type two words.

Analyze this.

What comes back looks good. The numbers, the insights, the tidy summary. But how do you actually know if it's right?

Last week I put ChatGPT through a proper test. A messy, multi-sheet sales file with codes, lookups, and calculations it had to figure out on its own. Then I verified the results myself with a data model in Excel.

There's a specific workflow that makes the difference between trusting AI blindly and actually being in control.

👉 Watch the test, and copy the workflow​

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One thing to keep in mind: this workflow is good for ad-hoc analysis, not recurring reporting. For that, build a deterministic model with Power Query and Power Pivot instead.

🤓 Geeky News

🫗 PivotTable #SPILL! generally available

When something blocks a PivotTable from expanding, you used to get a popup asking what to do. That popup is gone.

Instead, the PivotTable collapses into a single cell showing a #SPILL! error, the same way FILTER or SORT behaves when something's in the way.

Your data is safe. The PivotTable is still there. Clear the blockage when you're ready and it expands again.

This behavior is now generally available, starting with the current channel. If you're on monthly or semi-annual, you might get the popups for a while longer.

Meanwhile, another promising feature - PivotTable AutoRefresh - was removed from Beta and no word when it's coming back...

🤖 Copilot in Excel: rules and skills

The rest of June Excel updates were, predictably, about Copilot.

In addition to personalization, which covers all of your workbooks, you can set rules for a specific file.

You define how Copilot should behave in that workbook, formatting conventions, layout rules, which functions to use. Those rules travel with the file when you share it. No setup needed on the other end. The rules live in a sheet called .Rules.

There are also skills for repeatable tasks. Instead of re-explaining the same process every time ("build a DCF model," "refresh the monthly report"), you define it once as a skill and Copilot follows it on demand. You can use built-in skills or create your own. Each skill you create needs to be saved in a dedicated OneDrive folder.

Both rolling out to Microsoft 365 Insiders.

🤖 The rest of Copilot June updates

A lot landed this month across the Microsoft 365 apps.

Copilot Cowork, the agentic version that actually does tasks start to finish rather than just drafting them, is now generally available. It can browse the web, generate images, and pick its own model depending on the task. Now also on mobile.

When building a PowerPoint presentation, you can now point Copilot at a SharePoint library or OneDrive folder, so it pulls from your actual content instead of making things up. It can also follow brand templates.

Model choice has arrived in Word, including Anthropic's Claude, so you can pick what handles your edits. Deep citations now link to the specific paragraph in a Word or PowerPoint file Copilot pulled from, not just the file itself.

And Outlook now lets you select a section of a draft and ask Copilot to adjust just that part.

🤔 Did You Know?

...that Excel also has presentation mode?

I'm sure you know all about presenting in PowerPoint.

But if presenting data in Excel - maybe hard numbers, maybe a dashboard - you'd want to remove the distraction.

Hide the formula bar (View > uncheck Formula bar).

Hide the ribbon (Ctrl + Shift + F1).

Or do both at once by adding Full Screen View to the Quick Access toolbar.

Escape to go back.

(Thanks to Wyn Hopkins for sharing this tip at the Global Excel Summit.)

👏 From workarounds to models that actually scale

Aneta is a Chief Accountant, working with large datasets, complex reports, Power BI. She knew her way around Excel. But something wasn't quite right under the hood.

After completing Excel Data Modeling with Power Pivot & DAX, here's what she shared:

Now she designs models built to last instead of patched together to survive the week.

That's the difference Power Pivot makes when you finally learn it properly.

See you next week,

Leila

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