Twelve — the number of order

12 hours in a day (twice), 12 months in a year, 12 zodiac signs, 12 apostles. Twelve is a convenient number: divisible by 2, 3, 4 and 6. The Sumerians chose 12 as the basis of timekeeping over 4,000 years ago.

The Laws of the Twelve Tables (450 BC) — the first written code of laws of ancient Rome. They became the foundation of the entire Western legal tradition and the prototype of modern law.

The 12-bar blues progression is the foundation of modern popular music. Rock and roll, jazz and a huge part of the world repertoire from Chuck Berry to Led Zeppelin are built on it.