context: ###List of Questions
  (1) Suppose -b - 3*g = 2*b - 231, -310 = -4*b - 2*g. Suppose -5*k = -10, 5*k + b = 2*u - 0*u. What is the units digit of u?
  (2) What is the value of 40/180*45/(-20)?
  (3) What is prob of picking 3 u when three letters picked without replacement from xuuxxuc?
  (4) What is next in 112, 226, 346, 472, 604, 742?
  (5) What is 0.572882mm in nanometers?
q_1: (1) Suppose -b - 3*g = 2*b - 231, -310 = -4*b - 2*g. Suppose -5*k = -10, 5*k + b = 2*u - 0*u. What is the units digit of u?
q_2: (2) What is the value of 40/180*45/(-20)?
q_3: (3) What is prob of picking 3 u when three letters picked without replacement from xuuxxuc?
q_4: (4) What is next in 112, 226, 346, 472, 604, 742?
q_5: (5) What is 0.572882mm in nanometers?