Fatto generale: 30 is the minimum age for United States senators.
Fatto matematico: 30 is a primorial and is the smallest Giuga number.
Trivia: 30 is the consumption in pounds of candy annually per person in Denmark, the country with the highest candy consumption.
Data storica: January 30th is the day in 1889 that Archduke Crown Prince Rudolf of Austria, heir to the Austro-Hungarian crown, is found dead with his mistress Baroness Mary Vetsera in Mayerling.