Although 18 and σ(18) = 39 are not coprime, 18 is known to be asolitary number. 18 is the smallest number known to have this property; for 10, 14, and 15, their status as friendly or solitary is not known.
TheHebrew word for "life" isחי (chai), which has anumerical value of 18. Consequently, a custom has arisen in Jewish circles to give donations and monetary gifts in multiples of 18 as an expression of blessing for long life.[3][4]
InJudaism, in theTalmud;Pirkei Avot (5:25), Rabbi Yehudah ben Teime gives the age of 18 as the appropriate age to get married ("Ben shmonah esra lechupah", at eighteen years old to theChupah (marriage canopy)). (SeeComing of age,Age of majority).
TheAmidah prayer is also known Shemoneh Esrei as (sh'MOH-nuh ES-ray, which means "eighteen") because it has eighteen blessings.
In Hinduism, in theMahabharata, the number appears in 18 books (Parvas), the 18 chapters of theBhagavad Gita, the 18 days of theKurukshetra War, and the 18Akshauhini divisions of armies. There are also 18 major and 18 minorPuranas.
InChinese tradition, 18 is pronounced十八;shí bā and is considered a lucky number due to similarity with實發;shì fā 'definitely get rich', 'to get rich for sure'.[citation needed]
The minimum age at which one can purchase, rent, or buy tickets toNC-17-rated films or buy video games with anAdults Only rating.
In the UK, 18 is the legal age to purchase aBBFC "18" rated film.
In Japan, 18 is the minimum age at which one can purchase, rent, or buy tickets toR18+ rated movies or buy video games with aZ rating, although 20 is their cultural age of adulthood.
