When calling in for tech or warranty support for your computer, you will probably be asked for the computer’s serial number. It’s usually stamped or adhesed to the computer chassis, and may be called S/N or Service Tag on certain brands of systems.

Except it’s not always easy to find that sticker. Maybe your office is too dark or your eyes can’t focus on the tiny writing or your computer tower is inaccessible, half-buried under files and equipment. Or maybe the serial number has worn away from the underside of your laptop and can’t be read. You’ll want an better way to get that number.

Apple makes it super-easy — just click the Apple menu and then click About This Mac. But on a Windows computer, it’s not so obvious. Here’s a trick that usually works:

In Windows, open a Command Prompt window. If you don’t see Command Prompt on your Start menu, you can right-click your Start button to get to it. Or you can press Windows+R and type in cmd .

At the Command Prompt, type in:

wmic bios get serialnumber

and press Enter, and your serial number should appear!