Can the DUPLO My First Number Train fit on DUPLO tracks?
Not really - the wheels on "My First Number Train" are the DUPLO car wheels, so they will just about fit on straight and curved track, but they won't work on the points and bridge sections.

There isn't any track designed for the wheels in "My First Number Train", that's just designed to pulled around on the floor.

You can just about see a chassis in this picture - they are about to crash at the points: