A car is travelling at a uniform speed.
The driver sees a milestone showing a 2-digit number. After travelling for an hour the driver sees another milestone with the same digits in reverse order.
After another hour the driver sees another milestone containing the same two digits as in the first one but the two digits separated by a zero(0).
What is the speed of the car?
(In reply to
re: Divisibility by SilverKnight)
Yes, I could have posted a fuller explanation. In fact, I did just that earlier this evening for another puzzle based on divisibility rules.
In this case, a number of previous posts had already explained the relevant divisibility rules. So I decided to present a shorthand solution that showed how to derive the speed without deriving the milestones.