This article has information on locating the service tag (also referred to as the system serial number) using Command Prompt.
Using Command Prompt
For a tablet, on the Windows Tile Screen, swipe from bottom and click All Apps.
- Navigate to the Command Prompt Window in your computer.
- Scroll to the right till you get to Command Prompt.
- On the Command Prompt window, type wmic bios get serialnumber.
For a tablet, use the onscreen keyboard to input the command.
- Hit enter.
- Service Tag would be displayed.
Refer to the image below: