The surface area of any solid is the summation of all the areas of its faces. For a square prism, the surface area is therefore calculated through the equation,
A = 6e²
where A is area and e is the measure of the side.
From the given above, it is stated that the edge of the prism measures 6. Substituting this value to the equation above,
A = (6)(6²)
A = 216
Therefore, the surface area of the given prism is equal to 216 square units.