How far is Zhangdian District from Boshan District?

Zhangdian District is 42 kilometers away from Boshan District. According to Baidu map, the distance between Zhangdian District and Boshan District measured by the map is 4.2 cm, and the scale between the map and the actual distance is 1: 1000000, 4.2 cm * 100000 = 42 km, so the distance between Zhangdian District and Boshan District is 42 km.