def main():
  T = int(input())

  sequence = []
  for t in range(T):
    sequence.append([])

    row = input()
    for letter in row:
      sequence[t].append(int(letter))

  for seq in sequence:
    while len(seq) != 1:
      new_seq = []

      i = 0
      while i < len(seq)-1:
        tmp_ans = seq[i] + seq[i+1]

        if tmp_ans >= 10:
          tmp_ans = (tmp_ans % 10) + 1

        new_seq.append(tmp_ans)

        i += 1

      seq = new_seq

    print(seq[0])

main()