28. Teacher Zhou takes students to Los Angeles, USA, to participate in a math competition. The first match is held at 6 PM on May 31, Los Angeles time, which is 9 AM on June 1, Beijing time. Teacher Zhou's flight departs at 12:00 PM on May 28 (Beijing time) and arrives at 9:00 AM on May 28 (Los Angeles time). The average speed of the flight is 840 kilometers/hour, and the distance between Beijing and Los Angeles is $\qquad$ kilometers.
$10080$