Locating Your Product Serial Number
Use any of these methods to find your Mac mini serial number:
Look on the bottom of your Mac mini.
Choose Apple () from the menu bar, and choose About This Mac. Click the version
number beneath the words “Mac OS X” to cycle through the Mac OS X version
number, the build version, and the serial number.
Open System Information (in the Utilities folder in Launchpad) and click Hardware.