# __________________________PyMagic ;)______________________________
from collections import *
from math import *
from sys import *
from bisect import *
input=stdin.readline

# __________________________Fast I/O :)_____________________________

def inp(): return map(int,input().split())
def print_l(a): return stdout.write(" ".join(map(str,a))+"\n")
def print_s(a): return stdout.write(str(a)+"\n")

# __________________________Finally...______________________________

for _ in range(int(input())):
    r=int(input())
    k=sqrt(3)
    print(0.75*r*r*k)