"Eighteen" is a 2015 novel by J. A. Huss, a story about a teacher and his completely inappropriate attentions for a student who is 18

the genetic code encodes 20 amino acids that are used to build proteins

the density of chromium is 7.19 g/cm^3

Major Zero is a character in the Metal Gear Solid videogames

in several countries, 18 is the age of majority and the voting age

the number of natural satellites of the planet Mercury

92 Seconds to Midnight is an episode (s1e3) in the crime series "The Hat Squad", in which a known criminal robs an armored car and kills the people who worked with him

'71 is a 2014 thriller film set in Northern Ireland about a British soldier who becomes separated from his unit during a riot in Belfast

"Zero" is a song by American alternative rock band The Smashing Pumpkins. It is a single from their album "Mellon Collie and the Infinite Sadness"