Find the area of a square circumscribed around a circle of radius √15.

Since the square is circumscribed around a circle, the circle is inscribed.
The area of a square can be found through the radius of the inscribed circle using the formula:
S = 4 * r ^ 2,
where S is the area of the square, r is the radius of the circle around which the square is described.
Substitute the known value of the inscribed circle radius into the formula and find the area of the square:
S = 4 * ((√15) ^ 2) = 4 * 15 ^ 2 = 4 * 225 = 900 (conventional square units).
Answer: S = 900 conventional square units.