Two pieces of information can be obtained from the description of the side expansion diagram in the topic:

1, the height is 12cm.

2. The perimeter of the bottom surface is 12cm (the bottom surface is square, so each side is 3cm long).

So the volume is good:

3*3=9 is the bottom area.

The area of the bottom multiplied by the height is the volume: 9* 12= 108 cm2.