The calculated distance (air line) between Pak Shek Kok and Mong Kok is approximately 8 miles respectively 12 kilometers.
By car or train, the actual journey to Mong Kok is certainly longer, as only the direct route (as the crow flies) between Pak Shek Kok and Mong Kok has been calculated here.
Air line (approximately)
12 kilometers
7 nautical miles