My friend Rodrigo lives in apartment number 28 that is on the 6th floor of the building. Going up the stairs I see that there are no apartments on the ground floor and that each of the floors has the same number of doors.

**How many apartments are on each floor?**

#### Solution

**Each floor has 5 apartments**.

If we do the entire division of my friend's apartment number by the floor number 28/6 we get 4 with a remainder of 4. So I see there have to be 4 or more apartments per floor. If there were 4, apartment 28 would be on the 7th floor. If there were 6 apartments per floor, apartment 28 would be on the 5th floor so there have to be 5 apartments on each floor.