Nakona, I think your math is a bit fuzzy. A refresher, 1 section= 640 acres = 1 SQ mile or 1 mile x 1 mile.
Sking? The Yellowstone club is pioneer mtn. Warren Miller is the "director of Skiing" (what ever in the hell that means). The Yellowstone Club is an exclusive for the "rich" only area just to the South. Last spring they bought 1300 acres of Big Sky land adjacent to their boundary. This was Big Sky land that was developed with an old slow triple chair called Southern Comfort. Big Sky will continue to operate this part of the area and Club members will use it to access Big Sky skiing. Too bad its a one way deal, Big Sky pass holders will be able to ski this terrain but not travel to the Club.
The current expansion is below Nashville Basin on the north side in the area that Montana Backcountry Adventures has cat skied for the past 5-6 years. The cut trails are mostly rolling intermediate terrain similar to MR. K and Lobo. Intermediate terrain is somewhat lacking here and this will be a nice addition. Big Sky claims 3600 skiable acres which is suprisingly honest for a resort that tried to claim more vert. that J.H. (ski from the summit to the base, cross a parking lot and down a road to the lowest lift possible) Actually Big Sky currently covers 8 sections, 8 x 640=5120 acres, throw in the addtitonal 1200 and you are looking at 6300+ acres or terrain, not all of which is skiable, but damn it is BIG.