context: ###List of Questions
  (1) Calculate prob of sequence ddyy when four letters picked without replacement from ydyddydd.
  (2) What is next in 240, 198, 156, 114, 72, 30?
  (3) What is the value of 0 + -1 + (-3 - (-5 - -3))?
  (4) Suppose -s = 4*r - 45, -s - r + 4*r = -38. Calculate the remainder when 121 is divided by s.
  (5) How many centuries are there in 90116.68 millennia?
q_1: (1) Calculate prob of sequence ddyy when four letters picked without replacement from ydyddydd.
q_2: (2) What is next in 240, 198, 156, 114, 72, 30?
q_3: (3) What is the value of 0 + -1 + (-3 - (-5 - -3))?
q_4: (4) Suppose -s = 4*r - 45, -s - r + 4*r = -38. Calculate the remainder when 121 is divided by s.
q_5: (5) How many centuries are there in 90116.68 millennia?