A tree is as high as 25 (decimeter), which can provide 18 (cubic meter) shade every summer, and people can enjoy the cool below. The green space under the shade is about 40 (decimeter) long and 16 (decimeter) wide, covering an area of about 600 (decimeter square).

This is mine. Otherwise, it will be contradictory.

40× 16=640 square decimeter =6.4 square meters

6.4×2.5= 16 m3