Global Hardware 28 December 2019 - Christmas Week

[StarDoor]

SpokenTruth said:

StarDoor said:

Unfortunately, no. PS4 was at 53.4M on January 1st, 2017 and 73.6M on December 31st, 2017, so it sold 20.2M in 364 days.

https://www.sie.com/en/corporate/release/2017/170105.html
https://www.sie.com/en/corporate/release/2018/180109.html

Similarly (according to VGChartz,) Switch was at 29.6M on December 29th, 2018 and 49.8M on December 28th, 2019, which would also be 20.2M in 364 days.

Isn't that 365 days?  What day is missing?

If you add 364 days to January 1st, you get December 31st. The 20.2M figure doesn't include sales on January 1st, because that's the date of the previous sell-through announcement.