Sony, launch day: Eh, let's just call the OS version, 1.01.Well 360 is technically zero on a circle too so it makes a lick of sense to call the successor 1
And the system shall be called PS4, because that comes after 3.
MS, launch day: Eh, let's just call the OS version, 6.2.9781.0.
The next natural number after 360 is 1, so let's call it Xbox One.
What comes after 8?
MS: 10!
10!
Windows 10!