What is the S/N number? Where can I find them? May 21, 2016 08:44 Updated Follow S/N number is the serial number which can be found on the back of the packaging box Related articles What are the S/N and D/N numbers? Where can I find them? What are the system requirements to use the ZeRound? What is the Bluetooth operating range? How to reset my Password? Will my data be deleted if I remove the app from my phone?