Ok. So Sony announced that they sold 2.1mil as of 01/DEC.
And then they announced they have sold 4.2mil as of 28/DEC. Which means 2.1mil were roughly sold for December, and we also know that for most of December, ps4s were sold out.
Now come January 20th, PS4s are still sold out as of today. Which means for Jan 2014, we will assume ps4 sales could be something like 2mil again. (Unless Sony for some weird reason is making PS4s slower than they were making them in Dec.)
For February 2014, PS4 debuts in Japan, where pre-orders are said to reach 1million. So for February, we will assume ps4 sales are around 2 mil again.
For March 2014, lets say it slows down and sells 0.5mil.
4.2 +2 +2 +0.5 = 8.7ml. Crazy number.







