More than 60-million licences of Windows 8 have been sold since its launch in October 2012. 

Windows chief marketing officer and chief financial officer Tami Reller yesterday made the announcement at a JP Morgan Tech Forum hosted at International CES in Las Vegas.
The 60-million figure is the cumulative total of all Windows 8 instances, including upgrades and sales to OEMs for new devices.
The sales trajectory so far is similar to that of Windows 7, says Reller. There are current 1 700 certified systems for Windows 8 and Windows RT.

In addition, Microsoft has grown its developer support for the platform and more than 100-million apps have been downloaded from the Windows Store since it became generally available about two months ago.