Hecho general: 30 is the percentage of methane on Earth produced from the flatulence of domesticated cows.
Hecho matemático: 30 is a primorial and is the smallest Giuga number.
Trivia: 30 is the minimum age for United States senators.
Fecha histórica: 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.