Throughout the world, many numbers are considered unlucky, and are generally avoided at all costs. Keep in mind that the articles for the numbers 13 and 666 are separate from this article, because they are well-known enough to have their own pages. This page is for the the lesser known numbers.
Asian Numbers
4: Considered unlucky in China, because the word for "four" is similar to the word used for death. Because of this, many constructors would often omit the number four on their buildings, much like how some U. S. constructors would skip the thirteenth floor on their buildings.
9: This number is feared in Japan, because, much like with the Chinese word for death, the Japanese translation for the number 9 sounds eerily similar to the Japanese word used for torture or suffering.
39: In Afghanistan, the number 39 is said to be translated out as the Afghanistan word for "dead cow." It's also considered a slang word referring to a person who "procured prostitutes." Because of this fact, many Afghans tend to avoid this number if they were to come into contact with a vehicle that had the number 39 on its license plate.
European Numbers
17: This number functions very similarly to the number 13 in western countries. It is believed that this number is unlucky, because if you were to take the Roman numeral for this number, XVII, and if you were to rearrange it, it would spell out VIXI, which means "My life is over" in Latin. In Italy, Friday the 17th is considered an unlucky day, and not Friday the 13th in other countries.