2、36 8

3、6

5、25. 12(8π)

Analysis of 1, 6×5×8=240

2,24 ÷ 4 = 6,6× 6 = 36 (a square has four sides) 24 ÷ 12 = 2,2× 2× 2 = 8 (a cube has12 sides).

3. Cylinder-cone =12s× h-1/3× s× h =12sh =18 Cone volume: 1/3 s h=6.

5、s = 2πr×l = 2×π×0.5×8 = 8π= 25. 12