Find the least number of unit cubes to be added to the solid to form complete a cuboid.
The distance on a map between Town A and Town B is 24 cm. The actual distance between these two towns is 360 km. Find the ratio of the distance on a map to the actual distance between two towns.
A1 : 1500000
B1 : 150000
C1 : 150
D1 : 15