Where are the 2 square coming from

The problem states that the ends of the frustum are square. The area of any square is calculated by multiplying its side length by itself, which is the same as squaring the side length.

For example, if a square has a side length $s$, its area $A$ is given by:

$$A = s \times s = s^2$$

In the previous problem, the side lengths of the square ends were $10 \text{ cm}$ and $4 \text{ cm}$, so their areas were $(10 \text{ cm})^2$ and $(4 \text{ cm})^2$ respectively.