The way most people use Excel is about to look very outdated. In this walkthrough, I show you 10 practical ways I’m using Claude Cowork to automate spreadsheets by just describing what I want in plain English—clean this data, write me a formula, turn this into a chart—and it actually does it. No syntax, no Stack Overflow, no 45-minute tutorial rabbit holes. We start with the annoying stuff that wastes the most time: converting messy CSVs, text files, and even PDFs into clean Excel files with proper headers and formatting. Then I hand Claude a spreadsheet I’ve never seen before and ask it to explain what it does, walk through formulas, and flag risky logic (like hardcoded “top rep” cells that won’t update). After that, we go into automated error detection—duplicate IDs, future dates, negative quantities, totals that don’t match—and I show how it can fix issues while I recommend keeping a clean copy and adding a change log. From there, I use it to standardize messy lead data, write complex formulas (profit margin, running totals, discount flags, tiered commissions), summarize multi-sheet workbooks, pull business insights, generate exec summaries, build charts and dashboards, format reports to look professional, and export Excel into a polished PDF. If you learn this early, you’re going to have a real edge.