Wouldnt it make more sense to round to 53.4m or 54m? 

The XB1 was selling nil in Japan, so the difference is minimal. But the US makes up over 50% of sales, and I'm pretty sure it was also up in the UK as well, which makes up almost 1/2 of all European sales. Unless sales dropped 50% in mainland Europe, I don't see the XB1 doing only 7 million this year vs 8.6 million last year.

I don't think anything was said about either console being up YOY in the UK. I do remember that the XB1 was down YOY by a whole lot (>30%) on Black Friday week.

I'm pretty sure it wasn't down in the UK, though I did hear about the slump in black friday sales. 

So there is actually good reason to believe that XB1 sales outside the US are down YOY.

From July through September, the XB1 was up YOY by about 99.7K units on NPD. On the other hand, when Microsoft's FY17 Q1 numbers came out, Xbox hardware revenue was down YOY by 26% due to lower prices and lower volumes of consoles sold. Over a quarter drop in Xbox hardware revenue is nothing to sneeze at, but at the same time, the XB1 was doing a much better job in the US from July-September 2016 compared to the same time period in 2015. It's only one quarter, but it gives some perspective.

Ps4 is killing it according to this report. Sony in a position of power.

Both true prior to this report from.....superdata....someone came up with that name.....but now more so! Superdata! Prob more accurate than the VGC numbers. And by probably I mean I really like VGC.

The XB1 had the release of new hardware and price cuts, so...

But keep this in mind. If the XB1 was up YOY in the US, its hard to see the XB1 being down 15% WW. That would mean sales dropping 35-40% in the rest of the world, which I see as unlikely (which this report would indicate).

Thats one way to look at it, but then it makes more sense rounding 53.4 up to 55M than rounding it down to say 50M if dealing with half of tens. Then again, then they should have rounded the XB1 down from 26M to 25M and say sold a little over 25M

We only know about XB1 being up YOY for NA... and more specifically for the last 6 months of 2016. And even with that it didn't do well enough to outsell the PS4 in NA for the entire year. And you are also citing isolated incidents. Yes for a month or two or three it could have been up in the UK and even in NA, doesn't mean that all those other months that MS doesn't shout from the rooftops when it was down YOY it wasnt down by such an amount that overall it could be down YOY globally.

Whatever the case though, we can't know for certain. There is legitimacy to your assumptions as there is to mine. I am just going off the fact that MS has had a history so far this gen of touting every little success as much as they can... if MS were up YOY worldwide, trust me they would have said it.