Why did windows skipped 'Windows 9'

Microsoft Skipped ‘Windows 9′ Name Because Of Legacy Code Compatibility Issues. Microsoft surprised everyone while announcing ‘Windows 10′ as their name for the upcoming version of Windows couple of years back. 

But why did Microsoft decide to skip the most obvious name ‘Windows 9’? 

According to latest reports, Microsoft decided to go with Windows 10 branding to avoid issues related to Windows 95/Windows 98 legacy code. 

Microsoft dev here, the internal rumours are that early testing revealed just how many third party products that had code of the form if(version.StartsWith(“Windows 9″)) { /* 95 and 98 */ } else { and that this was the pragmatic solution to avoid that.

If Microsoft named it as Windows 9, all classic apps with the above code structure will treat it as either Windows 95 or Windows 98. So, Microsoft decided to avoid it by naming it Windows 10.