Fatto generale: 123 is the Notation for national and international telephone numbers Recommendation ITU-T Recommendation E.123 defines a standard way to write telephone numbers, e-mail addresses, and web addresses.
Fatto matematico: 123 is the 10^{th} Lucas number.
Trivia: 123 is the emergency telephone number in Colombia.
Data storica: May 2nd is the day in 1952 that the world's first ever jet airliner, the De Havilland Comet 1 makes its maiden flight, from London to Johannesburg.