You can find your devices serial number by one of the following methods.
1. Click the Apple icon at the top left of the screen.
2. Click “About This Mac”
3. Your serial number will be stated within the details window. You can copy the serial by highlighting the text and pressing Cmd + C.
1. On the underside of your mac there will be some text below the device type, check for the text “Serial”, the following numbers will be the device serial number.