Windows 10 is running on 110 million devices, Microsoft said yesterday as it introduced a new Surface Pro tablet, the Surface Book notebook and several Lumia smartphones, all of which run the OS.

"There are 110 million users running Windows 10 right now," said Panos Panay, the chief of the Surface team, during a two-hour presentation of the new hardware.

Panay's data point was the first time since late August that Microsoft has claimed a Windows 10 number. More than a month ago, Microsoft said Windows 10 was on 75 million machines.

The difference of 35 million supported the trend portrayed by third-party analytics vendors that measure operating system user share and usage share by tracking website visitors and page views.

Data from both U.S.-based Net Applications and Ireland's StatCounter have illustrated a slowdown in Windows 10 adoption during September, the second full month after the OS's July 29 launch. Net Applications, for example, said that Windows 10's September gains in user share, a proxy for the number of devices running the operating system, were less than a third of those in August. StatCounter's usage share numbers showed a similar slowdown in September.

Microsoft's 110 million described those running Windows 10, not downloads, the company confirmed. A spokeswoman declined to describe how the company tracks uptake, but presumably it does via Windows 10 activations, which it could easily tally from its logs.

Coincidentally, the 110 million was identical to what Computerworld came up with by analyzing Net Applications' user share for Windows 10, comparing it to Windows' overall user share, then multiplying the result against the 1.5 billion devices that Microsoft claims run Windows.

StatCounter's usage share numbers -- an indication of online activity because they're based on website page views -- showed a trough in Windows 10's growth on Sept. 20, then an upward swing that peaked on Sept. 26 and lasted through Oct. 3.

The usage upswell was noticeable when the data was charted, but an explanation was more difficult to discern. It may have simply been a more active stretch for Windows 10 users -- more online activity, in other words -- or it may have signaled that Microsoft pulled the upgrade trigger on a larger number of personal computers running Windows 7 or Windows 8.1.

Users of those operating systems have been allowed to "reserve" an upgrade since June. Microsoft then pre-loads the Windows 10 upgrade bits -- as much as 6GB worth -- to those devices, but staggers the notifications displayed on customers' computers to alleviate server overload.

Windows 10's usage share remains higher than Windows 7's at the same post-release point, but the gap has been shrinking, largely because Windows 7 launched later on the calendar -- October rather than July -- and thus accumulated impressive gains around the 2009 holidays as large numbers of consumers and some businesses bought new PCs near year's end.

Windows 10 should crack the 10% usage share mark for the first time on Sunday, reinforcing the impression that the free upgrade gave the OS about a one-month boost compared to Windows 7, which was a paid upgrade and also obtained through device purchases.