In the chess kingdom, the walls and roof of the palace, which has the shape of a rectangular parallelepiped

In the chess kingdom, the walls and roof of the palace, which has the shape of a rectangular parallelepiped 20 m long, 15 m wide and 25 m high, are painted with black and white square cells with a side of 5 inches. How many cells are there in the palace?

Let’s calculate the area of the walls and roofs of the royal palace.

S of the roof is equal to: 20 * 15 = 300 m2.

S of walls is equal to: (20 + 15) * 2 * 25 = 1750 m2.

S of the palace surfaces is equal to: 300 + 1750 = 2050 m2.

The area of a square cell is: 0.5 * 0.5 = 0.25 m2.

The number of cells on the surface of the palace is: 2050 * 0.25 = 8100 cells.