The free upgrade from Windows 7 and 8 to Windows 10 is doing wonders: In just under a month of general availability, Windows 10 is now running on 75 million devices.

Unsurprisingly, Windows 10 appears to be doing better than Windows 8: back in 2012, only 40 million Windows 8 licences were sold in the first month of availability. After six months, Windows 8 had risen to 100 million licences sold—but "sold" is likely to be a very different figure from how many devices were actually running Windows 8. So, 75 million devices running Windows 10 after a month is pretty darn good.

The 75 million figure comes directly from Yusuf Mehdi, a marketing chief at Microsoft. Mehdi also shared a few other semi-interesting Windows 10 tidbits: 90,000 different PC and tablet models have upgraded to Windows 10; Windows 10 has a presence in 192 countries (I wonder which one of the 193 UN member states is missing?); the Windows 10 Store has seen six times more downloads per device than Windows 8; and, most importantly, Cortana has told over half a million jokes.

Microsoft continues to roll out the free Windows 10 upgrade in waves. If you want to skip the queue, you can download Windows 10 directly. If you want to use your free Windows 10 upgrade licence to perform a clean installation, it's a little more complex but still doable. Oh, and of course, you should read our excellent review of Windows 10 while you wait for it to download.