The studio revealed the figure via a jubilant tweet, containing both multiple explanation points and enthusiastic capitalisation.

The news follows Mojang's January announcement that the XBLA incarnation of the block-based world builder outsold its PC-based older brother last year, as well as the more recent news that the XBLA version is due to sold on disc in certain territories. All in all, not bad for a game that was released in May of last year.
http://www.oxm.co.uk/51593/minecraft-xbox-360-sells-over-6-million-copies/