To check which operating system you have on your device please follow the below steps:
Android (requires 4.4 or later)
Go to the home screen of your device. Touch Settings then touch About Phone or About Device. From there, you can find the Android version of your device.
iOS on iPad/iPhone (requires iOS 10 or later)
Go to your iPad or iPhone's home screen, then tap Settings icon. From there, select General. Next, tap About. You'll see all of the information about your device, including the iOS version.
Amazon (requires 4.4. or later)
Go to Settings. Tap Device Options. Tap System Updates. Your OS version will be displayed toward the top of the screen.