Well, as some have pointed out, 10 is actually 9 in base 9.

It looks like they are bringing back windows to Windows though. To me Windows 8 has seemed more like just “Window” because it’s so hard to use multiple windows.

http://www.slate.com/blogs/future_tense/2014/09/30/microsoft_windows_10_operating_system_windows_8_was_so_bad_it_s_skipping.html