Given the nature of the Dragarean measurements of time and money, it would make sense to assume that Dragaerans use base-seventeen mathematics. Obviously, SKZB (or possibly Paarfi of Roundwood) has translated the values in the books to be ones that the reader will understand. This would make it much easier to express common values (such as 289, or 83,521) since they could be written as 10, or 1,000. Basically, their multiples of seventeen would be just as easy for them as multiples of ten are for us.