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The number 4 is omitted in some Chinese buildings.
Number4(四/肆; sì) is considered an unlucky number in Chinese because it is nearly homophonous to the word"death"(死sǐ). Due to that, many numbered product lines skip the "4": e.g., Nokia cell phones (before the Lumia 640, there is no series containing a 4 in the name), Palm PDAs, Canon PowerShot G's series (after G3 goes G5), etc. In East Asia, some buildings do not have a 4th floor. (Compare with the Western practice of some buildings not having a 13th floor because 13 is considered unlucky.)
In Hong Kong, some high-rise residential buildings omit all floor numbers with "4", e.g., 4, 14, 24, 34 and all 40–49 floors, in addition to not having a 13th floor. As a result, a building whose highest floor is number 50 may actually have only 35 physical floors. Singaporean public transport operator SBS Transit has omitted the number plates for some of its buses whose numbers end with '4' due to this, so if a bus is registered as SBS***3*, SBS***4* will be omitted and the next bus to be registered will be SBS***5*. Note that this only applies to certain buses and not others and that the final asterisk is a checksum letter and not a number. Another Singaporean public transport operator SMRT has omitted the '4' as the first digit of the serial number of the train cars as well as the SMRT BusesNightRider services.