> The relationship between the two would be that the number of cars is the number that is next in line when you have called out the indices (0, 1, 2, 3, 4, 5, 6

> The relationship between the two would be that the number of cars is the number that is next in line when you have called out the indices (0, 1, 2, 3, 4, 5, 6) of all the cars. But who thinks that way? I just see 7 cars, not an indexed listing. And anyway, the 0 indexed car doesn't exist.