How is surface area calculated for a two-dimensional square?

To calculate the surface area of a two-dimensional square, you use the formula that multiplies the length of one side by itself, which can also be expressed as length times width for rectangles. In the case of a square, since all four sides are equal, using length multiplied by itself (or width, since it's the same) provides a straightforward calculation. This yields the area that the square occupies on a flat surface.

The choice that proposes length plus width would lead to a perimeter measure rather than area, which is not relevant for calculating surface area. Dividing length by width provides a ratio but does not compute the area. Similarly, subtracting width from length does not yield a relevant measurement for area. Thus, the multiplication of length by width is the appropriate method to determine the surface area of a square, confirming that this approach is foundational in geometry.