A method of calculating theoretical power of wind farm based on extrapolation of anemometer tower data includes following steps. The inventive dental device comprises two interdental matrices for insertion into the interdental spaces, two retaining means for the interdental matrices and a spacer device for guiding the retaining means in parallel and for separating next but one adjacent teeth. The folded edge of the body side liner is then folded again to create a fully functional flap with the appearance of a leg elastic in the crotch area. The present invention also provides a system and an AAA server for charging a prepaid account. A current between 8 and 35 amperes may be used to mark the workpiece.