To make a rectangular wooden box [with cover] that is 8 decimeters long, 6 decimeters wide and 5 decimeters high, how many square decimeters of wood board does it need at least to make a wooden box

To make a rectangular wooden box [with cover] that is 8 decimeters long, 6 decimeters wide and 5 decimeters high, how many square decimeters of wood board does it need at least to make a wooden box

Emperor 888,
2 × (8 × 6 + 8 × 5 + 6 × 5) = 236 (square decimeter)

A cuboid wooden box, 7 in width. How many square decimeters of wood should be used to make this wooden box?

20 × 7.5 × 2 = 300 square decimeter
20 × 3 × 2 = 120 square decimeters
7.5 × 3 × 2 = 45 square decimeters
300 + 120 + 45 = 465 square decimeters

A cuboid wooden box, 6 decimeters long, 4 decimeters wide, with 20 square meters of wood, how many wooden boxes can be made at most?

(6 × 4 + 6 × 5 + 4 × 5) × 2 = 148 (square decimeter)
148 square decimeters = 1.48 square meters
20 △ 1.48 ≈ 13 (pieces)