https://arstechnica.com/gadgets/2019/03/windows-10-passes-800-million-devices/

Microsoft says that Windows 10 has reached more than 800 million devices. This is 100 million more than it had six months ago

When Windows 10 was launched—and when Windows on phones was expected to add tens of millions of devices—Microsoft set itself a target of one billion devices within two to three years. The end of its smartphone ambitions put paid to that hope, but Windows 10 is nonetheless the fastest-growing version of Windows of all time.