What Version is my Operating system?

 Mobile Devices

Android

• Select Settings > about phone/device. Look for "Android Version" This will tell you the Android operating system version.

iPhone

• Settings > General > About. You'll see the version number to the right of the "Version" entry on the About page

Computer Devices 

Mac 

• Go to the Apple menu (apple icon) in the corner of your screen, choose About This Mac. You should see the macOS name, such as macOS Mojave, followed by its version number.

Windows

• Select the Start button > Settings > System > About. Under Device specifications > System type, see if you're running a 32-bit or 64-bit version of Windows. Under Windows specifications, check which edition and version of Windows your device is running.

Alternatively:

• Press the Windows + R keyboard keys to launch the Run window, type winver and press Enter. This works in all versions of Windows.