t = int(input().strip())

for i in range(t):
  r = int(input().strip())
  #print(1.7320508 * r * (1 / 2) * (1 / 2) * 6)
  print(1.7320508 * r**2 * 3 / 4)
  #print(r * np.cos(np.pi / 6))