The number 11 (eleven) is the natural number following 10 and preceding 12. It is a prime number, the smallest two-digit number, and the first repdigit (a number composed of repeated instances of the same digit). Key Aspects of 11:
Mathematics: 11 is the 5th prime number. It is an odd, deficient, and semiprime-related number. It is also a Lucas prime and a repdigit (11). Idioms & Culture:
“Up to eleven”: A phrase popularized by the film This Is Spinal Tap to describe pushing something beyond normal limits.
“The eleventh hour”: Refers to the last possible moment or an emergency, often referencing the Parable of the Workers in the Vineyard or the Doomsday Clock. Science: 11 is the atomic number of Sodium (Na).
History/Religion: In Northern Ireland, the “Eleventh Night” refers to bonfires lit on the eve of the Battle of the Boyne.
This video provides a fun way to learn and practice the 11 times table: Multiply by 11’s! | All Mixed Up Jack Hartmann Kids Music Channel YouTube · Aug 25, 2025