Find last location of iPad, not connected to Wi-Fi and off
The last location the device was online and connected to the internet may have been sent and recorded in Find My iPhone if that feature was enabled on the iPad. 

Visit iCloud and log in with the Apple ID you use on your iPad. Then, go to find my iPhone. Here you will be able to see the last location the device was connected. If it does not have cellular this will only show the last place the device had a WiFi signal.