Special care may be taken to avoid occurrences or reminders of the number 4 during festive holidays, or when a family member is sick, especially in Chinese culture. Similarly, 14, 24, 42, etc. are also to be avoided due to the presence of the digit 4 in these numbers. In these countries, these floor numbers are often skipped in buildings, ranging from hotels to offices to apartments, as well as hospitals. Table number 4, 14, 24, 42, etc. are also often left out in wedding dinners or other social gatherings in these countries. In many residential complexes, building block 4, 14, 24 etc. are usually replaced with block 3A, 13A, and 23A.
In Cantonese-speaking regions in China, 14 and 24 are considered more unlucky than the individual 4, since 14 sounds like "die for sure" and 24 like "easy to die".
http://en.wikipedia.org/wiki/Tetraphobia