Tetraphobia

Tetraphobia is a fear of the number 4. It is a superstition found most often in East Asian areas, for example China, Japan, Korea, and Taiwan.

An elevator in Shanghai – floor numbers 4, 13 and 14 are missing

The Chinese word for four (四, pinyin: sì, jyutping: sei³), sounds very similar to the word for death (死, pinyin: sǐ, jyutping: sei²).

Chinese people take care not to use the number 4 during important holidays, or if someone in the family is sick. Numbers such as 14, 24, and so on, are not used because they also have the number 4 in them. Buildings sometimes do not have floors with these numbers, apartments and hotels do not have rooms with number 4, 14, 24 and so on. Table number 4, 14, 24, may be often left out in wedding dinners or other social activities in these countries. Where there are a lot of apartment buildings, buildings that should be 4, 14, 24, are called 3A, 13A, 23A, and so on.

In Hong Kong, some apartments such as Vision City and The Arch do not have the floors from 40 to 49. Immediately above 39/F is 50/F, leading many who do not know about tetraphobia to think that some floors are missing.

The Chinese start numbering their military aircraft with the number 5, such as the fighter plane "Shenyang J-5". The Taiwanese and the South Korean navies do not use the number 4 when giving flag numbers to their ships.

In cities where East Asian and Western cultures come together, like Hong Kong and Singapore, it is possible in some buildings that both 13 and 14 are left out as floor numbers, along with all the other 4s.

In Korea, tetraphobia is not as important, but the floor number 4 is almost always left out in hospitals. In other buildings, the fourth floor is sometimes named "F" (Four) instead of "4" in elevators. Apartment numbers with a lot of the number 4 (such as 404) are hard to sell, and often they are not worth as much money.