13 (number)


13 is the natural number following 12 and preceding 14.
Folklore surrounding the number 13 appears in many cultures around the world: one theory is that this is due to the cultures employing lunar-solar calendars. This can be witnessed, for example, in the "Twelve Days of Christmas" of Western European tradition.

In mathematics

The number 13 is a prime number, happy number and a lucky number. It is a twin prime with 11, as well as a cousin prime with 17. It is the second of only 3 Wilson primes: 5, 13, and 563. A 13-sided regular polygon is called a tridecagon.

List of basic calculations

Division123456789101112131415
13 ÷ x136.54.3.252.62.11.1.6251.1.31.1.0810.90.8
x ÷ 130.0.0.0.0.0.0.0.0.0.0.0.11.1.

Exponentiation1234567891011
1313169219728561371293482680962748517815730721106044993731378584918491792160394037
x181921594323671088641220703125130606940169688901040754975581388825418658283291000000000000034522712143931

In languages

Grammar

In Germany, according to an old tradition, 13, as the first compound number, was the first number written in digits; the numbers 0 through 12 were spelled out. The Duden now calls this tradition outdated and no longer valid, but many writers still follow it.

In English

Thirteen is one of two numbers within the teen numerical range, along with fifteen, not derived by cardinal numeral and the teen suffix; instead, it is derived from the ordinal numeral.

In religion

Islam

In Shia, 13 signifies the 13th day of the month of Rajab, which is the birth of Imam Ali.

Catholicism

In Catholic devotional practice, the number thirteen is also associated with Saint Anthony of Padua, since his feast day falls on June 13. A traditional devotion called the Thirteen Tuesdays of St. Anthony involves praying to the saint every Tuesday over a period of thirteen weeks. Another devotion, St. Anthony's Chaplet, consists of thirteen decades of three beads each.

Sikhism

According to famous Sakhi or the story of Guru Nanak Dev Ji, when he was an accountant at a town of Sultanpur Lodhi, he was distributing groceries to people. When he gave groceries to the 13th person, he stopped because in Gurmukhi and Hindi the word 13 is called terah, which means yours. And Guru Nanak Dev Ji kept saying, "Yours, yours, yours..." remembering God. People reported to the emperor that Guru Nanak Dev Ji was giving out free food to the people. When treasures were checked, there was more money than before.

Judaism

  • In Judaism, 13 signifies the age at which a boy matures and becomes a Bar Mitzvah, i.e., a full member of the Jewish faith.

    Wicca

A common tradition in the religion Wicca holds that the number of members for a coven is ideally thirteen, though this tradition is not universal.

Luck

Bad

The number 13 is considered an unlucky number in some countries. The end of the Mayan calendar's 13th Baktun was superstitiously feared as a harbinger of the apocalyptic 2012 phenomenon. Fear of the number 13 has a specifically recognized phobia, triskaidekaphobia, a word first recorded in 1911. The superstitious sufferers of triskaidekaphobia try to avoid bad luck by keeping away from anything numbered or labelled thirteen. As a result, companies and manufacturers use another way of numbering or labelling to avoid the number, with hotels and tall buildings being conspicuous examples. It is also considered unlucky to have thirteen guests at a table. Friday the 13th has been considered an unlucky day.
There are a number of theories as to why the number thirteen became associated with bad luck, but none of them have been accepted as likely.
;The Last Supper: Jesus Christ's Last Supper, there were thirteen people around the table, counting Christ and the twelve apostles. Some believe this is unlucky because one of those thirteen, Judas Iscariot, was the betrayer of Jesus Christ. From the 1890s, a number of English language sources relate the "unlucky" thirteen to an idea that at the Last Supper, Judas, the disciple who betrayed Jesus, was the 13th to sit at the table.
;Knights Templar: On Friday, 13 October 1307, King Philip IV of France ordered the arrest of the Knights Templar, and most of the knights were tortured and killed.
;Full moons: A year with 13 full moons instead of 12 posed problems for the monks in charge of the calendars. "This was considered a very unfortunate circumstance, especially by the monks who had charge of the calendar of thirteen months for that year, and it upset the regular arrangement of church festivals. For this reason, thirteen came to be considered an unlucky number." However, a typical century has about 37 years that have 13 full moons, compared to 63 years with 12 full moons, and typically every third or fourth year has 13 full moons.
;A suppressed lunar cult: In ancient cultures, the number 13 represented femininity, because it corresponded to the number of lunar cycles in a year. The theory is that, as the solar calendar triumphed over the lunar, the number thirteen became anathema.
;Hammurabi's code: There is a myth that the earliest reference to thirteen being unlucky or evil is in the Babylonian Code of Hammurabi, where the thirteenth law is said to be omitted. In fact, the original Code of Hammurabi has no numeration. The translation by L.W. King, edited by Richard Hooker, omitted one article: If the seller have gone to fate, the purchaser shall recover damages in said case fivefold from the estate of the seller. Other translations of the Code of Hammurabi, for example the translation by Robert Francis Harper, include the 13th article.

Good

  • France: 13 was traditionally considered a lucky number in France prior to the First World War, and was used in numerical form as a good luck symbol on postcards and charms.
  • Italy: 13 was the lucky number in the Italian football pools. The Italian expression "fare tredici" means to hit the jackpot.
  • United States: Colgate University also considers 13 a lucky number. They were founded in 1819 by 13 men with 13 dollars, 13 prayers and 13 articles. In fact, the campus address is 13 Oak Drive in Hamilton, New York, and the male a cappella group is called the Colgate 13.

    Other

A baker's dozen, devil's dozen, long dozen, or long measure is 13, one more than a standard dozen. The thirteenth loaf is called the vantage loaf because it is considered advantageous overall to get 13 loaves for the price of 12.
In a tarot card deck, XIII is the card of Death, usually picturing the Pale Horse with its rider.

Age 13

The number 13 is a recurring motif in American heraldry. The first flag of the United States bore thirteen stripes, alternating red and white, and thirteen white stars in the blue union, representing the Thirteen Colonies from which the United States was created and the thirteen states in the new nation respectively. This is also reflected in the number of rays on the Flag of Arizona.
The Great Seal of the United States bears many images of the number thirteen. On the Seal's obverse, the overhead glory bears thirteen stars. The chest shield in front of the spread eagle bears thirteen stripes. The eagle's right talon holds the Olive Branch of Peace, bearing thirteen olives and thirteen olive leaves. The eagle's left talon holds the Weapons of War, consisting of thirteen arrows. The eagle's mouth holds a scroll bearing the national motto "E Pluribus Unum". On the Seal's reverse, the unfinished pyramid consists of thirteen levels.

In sports