There are 2 faulty odometer problems posted.
I believe that these problems can be solved by taking the numbers shown on the odometers as numbers in the base 9 and finding their values in base 10. For example: In the problem where the odometer skips 9 the faulty odometer registers 120. Changing this to base 10 yields 99 which was given as the answer.
In the problem where the odometer skips 8 the number registered was 2197. If we change this to base 10 we get 1627 which is the answer I got by a different method although it doesn't match the alleged answer of 1728.