Windows 10 marks 400 million installs on active devices.
Microsoft announced at the Ignite conference in Atlanta, Georgia that Windows 10 had passed 400 million installs on active devices.
Active devices meaning devices that have been active in the last 28 days. These devices cut across desktop computers, tablets, phones, Surface Hubs, Xbox One consoles, and even HoloLens headsets.
This is a nice achievement for Microsoft although this is far from the original 1 billion target slated for 2018. Microsoft has revised this target as it became clear that the target was unrealistic. Microsoft still wants to hit its target of 1 billion installs but is no longer adamant about the duration. Techradar reports that if the rate remains constant at this level going forward – which isn't a particularly wise assumption to make, but doing it anyway – it'll take Microsoft another three years to reach a billion devices; in other words, that won't happen until September 2019.

http://www.flashitsolutions.com/windows-10-marks-400-million-installs-on-active-devices/