new_contents: def num_digits(n: int) -> int:
      """
      Find the number of digits in a number.
  
      >>> num_digits(12345)
      5
      >>> num_digits(123)
      3
      """
      digits = 0
      while n > 0:
          n = n // 10
          digits += 1
      return digits
  
  
  if __name__ == "__main__":
      print(num_digits(12345))   # ===> 5
  
subject: Create number_of_digits.py (#1975)