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
Divisibility by Nick Hobson)
Nick,
While your points are true, it may not be obvious WHY it's true. You might want to show why Milestones 1 and 3 imply (c)... and why the Milestones 1 and 2 imply (a) and (b).
Otherwise... it is roughly equivalent to saying...
Milestones 1, 2, and 3 tell us the speed is 45 mph.
True.... but not all that explanatory.