new_contents: number = 201328361572
  maxDigit = -1
  
  # convert number into unique set of digits and iterate over it
  for c in set(str(number)):
      # parse back to int and compare vs known max
      i = int(c)
      if i > maxDigit:
          maxDigit = i
  
  print(maxDigit)
  # > 8
  
subject: Add greatest digit in number with python in math