Simple way to view build number
Press Win+R.
Type winver.
Press Enter:
You would be able to view the build number:
Other methods to view build number
Command prompt
Run command prompt (cmd.exe).
Type systeminfo and press Enter:
Registry
Launch the registry editor:
Open the key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
Find a value named CurrentBuildNumber and view the build number in the Data column: