1. A cube glass water tank without a lid, with a side length of 7 decimeters. How many square decimeters of glass are needed to make this water tank?

7*7*5=245 square decimeters

2. A cube food packaging box made of cardboard with an edge length of 30 cm. How many square decimeters of cardboard are needed to make 100 of these boxes? If a layer of trademark is affixed around each packaging box, how many square decimeters of trademark paper are needed for 100 packaging boxes?

(1) 30*30*6*100=540000 square centimeters=5400 square decimeters

(2) 30*30*4*100=360000 square centimeters=3600 square meters Decimeter

3. What does the four sides mean? Does it include up, down, left and right?

Surround means not including the top and bottom.

4. After cutting off the height of a cuboid by 2 cm, you will get a cube with an edge length of 5 cm. Find the surface area of ??the original cuboid.

2+5=7 centimeters (height of the cuboid)

(5*5+5*7*5*7)*2=95*2=190 square centimeters.