13. In a new nine-story building, where the first floor is allocated for stores, Sergei's family received apartment 211. On which floor and in which entrance is this apartment located, if on the third floor of one of the entrances of this building are apartments from 55 to 60? (All entrances and floors are the same.)
13. Since there are 6 apartments on one floor in one entrance (60-54=6), there are 48 apartments on eight floors of one entrance. Since $211=48 \cdot 4 + 19$, apartment 211 is in the fifth entrance, and since $19=6 \cdot 3+1$, this apartment is on the fifth floor.