Here is the answer from the Apple Support website:
https://support.apple.com/en-us/HT201471
Here is a more detailed guide from the Macworld UK website:
http://www.macworld.co.uk/how-to/ipad/how-identify-which-ipad-you-have-3528437/
Here is the answer from the Apple Support website:
https://support.apple.com/en-us/HT201471
Here is a more detailed guide from the Macworld UK website:
http://www.macworld.co.uk/how-to/ipad/how-identify-which-ipad-you-have-3528437/