The calculated distance (air line) between Sham Tseng and Mong Kok is approximately 8 miles respectively 14 kilometers.
By car or train, the actual journey to Mong Kok is certainly longer, as only the direct route (as the crow flies) between Sham Tseng and Mong Kok has been calculated here.
Air line (approximately)
14 kilometers
7 nautical miles