Yasir Mahmood / MakeUseOf By Yasir Mahmood Published Oct 13, 2026, 11:00 AM EDT Yasir is a Mechanical Engineer who writes about tech at MUO, covering Windows, Productivity, Security, and the Internet. His interest in autonomous systems keeps him constantly tinkering with both hardware and software. His tech writing journey began during his junior year of engineering, leading him to Android Police before joining MUO. He focuses on making technology accessible, whether he's troubleshooting Windows issues, exploring productivity tools, or explaining security risks in plain English. For Yasir, the best way to do this is to actually use the tools and run into the same problems readers face. When he's not writing or engineering, you'll find Yasir watching Impractical Jokers and genuinely laughing at pranks he's seen a dozen times before. Sign in to your MakeUseOf account Add Us Like Like follow Follow followed Followed Thread Log in Here is a fact-based summary of the story contents: Try something different: Show me the facts Explain it like I’m 5 Give me a lighthearted recap A colleague sends over a quarterly sales report; the totals look tidy, and the deadline says I should paste them straight into my own slides. I don't. A workbook someone else built tends to carry quiet problems that never show up as errors, so the numbers on screen can be wrong while every cell looks fine.

Before I reuse any figure, I spend about five minutes on five checks. None of them needs an add-in, since most rely on tools like the formula debugger hiding in Excel's Formula Auditing group. I run them in the order I'd open the file.

Screenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodCloseScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir Mahmood The first thing I notice on a borrowed workbook is the yellow bar under the ribbon. In my spreadsheet, it read "Automatic update of links has been disabled," which means some cells pull values from a different file. If that file lives on a colleague's laptop, those numbers are frozen at whatever they were the last time someone saved.

To see what's linked, go to Data > Workbook Links. The pane listed a file called CommissionRates.xlsx, and clicking any Commission cell showed that file's full path inside a VLOOKUP formula. The pane also flagged that the link existed in a defined name and in a hidden row, two places I'd never scan by hand.

Formulas > Name Manager confirmed it. A name called RegionTargets pointed at the outside workbook, even though no cell used it. If you can get the source file, refresh the link. If you can't, Break all converts every linked formula into its current value, so the report stops depending on a file you'll never see.

Breaking links can't be undone. Save a copy of the workbook first so you can still see which formulas pointed where.

Screenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodCloseScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir MahmoodScreenshot by Yasir Mahmood Hidden rows are easy to miss because Excel doesn't announce them. The only clue is the row numbers. In the sales sheet, row 14 sat directly above row 18, and row 30 jumped to 32. Four orders were tucked away, and all four were cancelled.

The catch is that SUM ignores visibility. The Sales Amount total read $130,210.74, which included $25,811.64 of cancelled orders. Typing =SUBTOTAL(109, H2:H41) returned $104,399.10, the visible rows only, which is a good example of why SUBTOTAL is often the safer choice over SUM. That figure matched the summary sheet to the cent.