If the iPad has the new lightning connector cable with the very small connector on the one end, it is the iPad 4. If the cable that came with the iPad looks like an old iPod Touch or iPhone cable, it is the iPad 3.
You can also go to Settings>General>About>Model and you can see your model number. Type that into a Google search and that will tell you what version you have.
Easy way to tell the iPad 3 from the iiPad 4 is the connector. If it has the very small Lightning connector, its an iPad 4.
If its got the larger 30 pin connector its an older iPad. (either 2 or 3)
Now to be sure what iPad you have, you can go here:
And enter your serial number and it will tell you exactly what type of iPad it is.
Your serial number can be found on the back of the iPad towards the bottom.
You can also identify the iPad by its model number. Simply go into Settings->General->About->Model
Type the model number into google, and it will likely tell you what it is. Or you can post it here and we'll tell you.
- https://selfsolve.apple.com/agreementWarrantyDynamic.do. This will show the make and model of the device.
Also very good advice, but I might add that this website requires the serial number for the device, which can be found by going to Settings, then General, then About, and scroll to Serial Number, or printed on the back of the iPad with the small print at the bottom.