A 2.5m long cuboid wood has a square bottom and a side length of 3DM. If the wood is said to be divided into three sections, how many square decimeters will the surface area increase? Tell me why

A 2.5m long cuboid wood has a square bottom and a side length of 3DM. If the wood is said to be divided into three sections, how many square decimeters will the surface area increase? Tell me why

Four surfaces are added
Surface area increased: 3 * 3 * 4 = 36 square decimeters