Microsoft Surface tablets sold merely 1.7 million units in 8 months since launch

How did this 1.7 million number come up, though? After all, it’s true that Microsoft has never officially released sales figures for its Surface tablets. Buried deep in the K-10 filing however are Surface tablet revenues. The number stands at $853 million, which is even less than the $900 million write-down Microsoft announced earlier.
Microsoft chief executive Steve Ballmer earlier said that the company has "built more devices than [it] could sell." Still, a second generation Surface is likely coming as the tablet market as a whole continues growing.
source: Microsoft Form K-10, GeekWire