Which number is considered unlucky in East Asia?
3
4
12
40
Words "four" and "Death" have very similar pronunciation in Chinese, Vietnamese, Korean and Japanese. In East Asia many buildings do not have a 4th floor. Some high-rise residential buildings omit all floor numbers with "4", e.g., 4, 14, 24, 34 and all 40–49 floors. 
reach: rather globalChinaEast AsiaFar EastJapanKorealucknumbersSouth KoreaVietnam
Answers by country
3
4
12
40
answers
 South Korea
South Korea27
 Kazakhstan
Kazakhstan23
 Greece
Greece23
 Singapore
Singapore23
 Japan
Japan21
 Canada
Canada39
 Russia
Russia168
 Republic of Ireland
Republic of Ireland33
 Australia
Australia63
 the United States
the United States304
 Vietnam
Vietnam19
 Ukraine
Ukraine121
 Belarus
Belarus19
 Switzerland
Switzerland52
 the United Kingdom
the United Kingdom182
 Austria
Austria65
 Poland
Poland14436
 the Philippines
the Philippines39
 India
India97
 Germany
Germany502