As is well known, Chinese people have an aversion for number 4, as 'four' in Chinese sounds like 'death'. So what do hotels do about the 4th floor?
The usual solution is just to omit it. Here are the buttons in the lift of a hotel in Tainan. It goes from the 3rd floor to the 5th floor, and nobody has to stay on the 4th floor.
However, there is another solution. Here are the buttons in the lift of a hotel in Kaohsiung, where the 4th floor is re-labelled as A Floor.
The trouble with this is that not everyone understands it. I saw one couple enter the lift, look at their key, and then go back to the registration desk to ask what was meant by A floor. But it does mean that nobody has to stay on the 4th floor, even if finding your room might be a bit confusing!