If the same brick is used to pave the floor, 9600 pieces of square bricks with a side length of 0.3 decimeters are needed; if the square bricks with a side length of 0.4 decimeters are used, how many pieces are needed?

If the same brick is used to pave the floor, 9600 pieces of square bricks with a side length of 0.3 decimeters are needed; if the square bricks with a side length of 0.4 decimeters are used, how many pieces are needed?

The total area of the ground is 0.3 × 0.3 × 9600 square decimeters
The area of square brick with side length of 0.4 decimeter is 0.4 × 0.4 square decimeter
So 0.3 × 0.3 × 9600 / 0.4 × 0.4 = 5400 (pieces)