In this case numerical order tells you that the cleaning was done in the order Fifth, Sixth, Seventh. Since this game is asking you to list cleanings in chronological order, then the question is effectively telling you that they are done in chronological order with Fourth before Fifth and Fifth before Sixth.
The question does not tell you that they are done in numerical order with each street immediately after the other
. I believe that you may be assuming that final phrase when you read this question. It is possible for these three streets to be cleaned in numerical order with the other five streets out of numerical order.
Let me know if this helps!