One of the most surprising aspects of yesterday's Microsoft event was the name of its new operating system: Windows 10. Not Windows 8.2 or Windows 9... but Windows 10. When asked about Windows 10's name, Windows chief Terry Myerson and Joe Belfiore avoided a direct answer, instead joking about how 'seven ate nine' and then lamely saying how the 'breadth of the product family' justifies the grandiose name. So, really, why did Microsoft call it Windows 10 instead of Windows 9?