fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)
              

fun printAns [] = ignore ()
  | printAns (h::tl) =
    let
        val hReal = Real.fromInt h
        val area = 3.0 * hReal * hReal * (Math.sqrt 3.0) / 4.0
    in
        (
          print (Real.toString area ^ "\n");
          printAns tl
        )
    end


val () =
    let
        val t = readInt ()
        val r_s = List.tabulate (t, fn _ => readInt ())
    in
        printAns r_s
    end