In spoken English, the numbers 13 and 30 are often confused. When carefully enunciated, they differ in which syllable is stressed: 13 i// vs. 30 //. However, in dates such as 1300 ("thirteen hundred") or when contrasting numbers in the teens, such as 13, 14, 15, the stress shifts to the first syllable: 13 //.
Strikingly similar folkloric aspects of the number 13 have been noted in various cultures around the world: one theory is that this is due to the cultures employing lunar-solar calendars (there are approximately 12.41 lunations per solar year, and hence 12 "true months" plus a smaller, and often portentous, thirteenth month). This can be witnessed, for example, in the "Twelve Days of Christmas" of Western European tradition.
- 1 In mathematics
- 2 In religion
- 3 Lucky and unlucky
- 4 Age 13
- 5 In sports
- 6 In TV and films
- 7 References
The number 13 is the sixth prime number, and the smallest emirp (a prime that is a different prime when reversed). It is also a Fibonacci number, a happy number, the third centered square number, and one of only 3 known Wilson primes.
Since 52 + 122 = 132, (5, 12, 13) forms a Pythagorean triple.
There are 13 Archimedean solids, and a standard torus can be sliced into 13 pieces with just 3 plane cuts. There are also 13 different ways for the three fastest horses in a horse race to finish, allowing for ties, a fact that can be expressed mathematically by 13 being the third ordered Bell number.
List of basic calculations
- In all Germanic languages (such as English and German), 13 is the first compound number (in German dreizehn); the numbers 11 and 12 have their own names (in German elf and zwölf).
- The Romance languages use different systems: In Italian, 11 is the first compound number (ùndici), as in Romanian (unsprezece), while in Spanish and Portuguese, the numbers up to and including 15 (Spanish quince, Portuguese quinze), and in French up to and including 16 (seize) have their own names.
- Like in Italian, in many other languages, 11 is the first compound number, e.g. in Arabic, Chinese, Hungarian, Swahili.
- This is also the case in most Slavic languages, Hindi-Urdu and other South Asian languages.
In Germany, according to an old tradition, 13 (dreizehn) as the first compound number was the first number written in digits; the numbers 0 (null) through 12 (zwölf) were spelled out. The Duden (the German standard dictionary) now calls this tradition (which was actually never written down as an official rule) outdated and no longer valid, but many writers still follow it.
For the English language, different systems are used: Sometimes it is recommended to spell out numbers up to and including nine or ten or twelve, like formerly in German, or even ninety-nine or one hundred. Another system spells out all numbers written in one or two words (sixteen, twenty-seven, fifteen thousand, but 372 or 15,001 ).
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 for the saint every Tuesday over a period of thirteen weeks. Another devotion, St. Anthony's Chaplet, consists of thirteen decades of three beads each.
According to famous Sakhi (Evidence) or 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.
- 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 (counts as a member of Minyan).
- The number of principles of Jewish faith according to Maimonides.
- According to Rabbinic commentary on the Torah, God has 13 Attributes of Mercy.
- The number of circles, or "nodes", that make up Metatron's Cube in Kaballistic teachings.
The number 13 had been considered sinister and wicked in ancient Iranian (Persian) civilization and Zoroastrianism. Since beginning of the Nourooz tradition, the 13th day of each new Iranian year is called Sizdah Be-dar, and this tradition is still alive among Iranian people both within Iran and abroad. Since Sizdah Be-dar is the 13th day of the year, it is considered a day when evil's power might cause difficulties for people. Therefore people leave urban areas for one day and camp in the countryside. Even in the current post-1979 Revolution era, and despite the wishes of Islamic government, this tradition continues to be practiced by the majority of the population throughout Iran.
Lucky and unlucky
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 coined 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 labeling to avoid the number, with hotels and tall buildings being conspicuous examples (thirteenth floor). It's also considered unlucky to have thirteen guests at a table. Friday the 13th has been considered the unluckiest day of the month. 
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: At 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.
- 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 repressed lunar cult: In ancient cultures, the number 13 represented femininity, because it corresponded to the number of lunar (menstrual) cycles in a year (13 x 28 = 364 days). The theory is that, as the solar calendar triumphed over the lunar, the number thirteen became anathema.
American born Horror-Punk singer and musician Joseph Poole (Murderdolls) uses the name Wednesday 13 as his stage name, taking "Wednesday" from the girl Wednesday from the Addams Family and 13 from Friday the 13th.
American country-pop singer-songwriter Taylor Swift was born on December 13. She considers 13 her lucky number due to lucky events happening to her when the number appears (her first album going gold in 13 weeks, being seated at awards shows in the 13th seat, row or section). She also wears the number written on her hand at her concerts so she has it with her everywhere she goes.
The band Big Star wrote a song called 13.
American alternative rock band, Pixies recorded "Number 13 Baby" for their Doolittle LP. The lyrics to the song include the line: "Standing in her chinos shirt pulled off clean, gotta tattooed tit say number 13"
Colgate University also considers 13 a lucky number. They were founded in 1819 by 13 men with 13 dollars, 13 prayers and 13 articles. (To this day, members of the Colgate community consider the number 13 a good omen.) In fact, the campus address is 13 Oak Drive in Hamilton, New York, and the male a cappella group is called the Colgate 13.
In the Mayan Tzolk'in calendar, trecenas mark cycles of 13 day periods. The pyramids are also set up in 9 steps divided into 7 days and 6 nights, 13 days total.
In the standard 52-card deck of playing cards there are four suits, each of 13 ranks.
In a tarot card deck, XIII is the card of Death, usually picturing the Pale horse with its rider.
A 24-hour clock uses the number 13 in the form of 13:00-13:59, to represent the fourteenth hour of its 24 hour cycle.
A baker's dozen, devil's dozen, long dozen, or long measure is 13, one more than a standard dozen.
- 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 (is qualified to be counted as a member of Minyan).
- This is the first year a person is considered a teenager.
- The United States of America was created from thirteen British colonies and as such, the number thirteen is a commonly-recurring motif in American heraldry. For example, there are thirteen stars on the Great Seal of the United States and there are thirteen stripes on the American flag.
- The first flag of the United States bore thirteen stripes, alternating red and white, and thirteen white stars in the blue union. The thirteen stripes represented the Thirteen Colonies from which the United States was created, and the thirteen stars represented the number of states in the new nation. When two new states were added to the Union in 1795, the flag bore fifteen stars and fifteen stripes. With the addition of five new states in 1818, the number of stripes was re-set and permanently fixed at thirteen.
- The Great Seal of the United States bears many images of the number thirteen, representing the Thirteen Colonies from which the United States was created. On the Seal’s observe, the overhead glory bears thirteen stars. The chest shield in front of the spread eagle bears thirteen stripes (seven white and six red). In the eagle’s right talon, it holds the Olive Branch of Peace, bearing thirteen olives and thirteen olive leaves. In the eagle’s left talon, it holds the Weapons of War, consisting of thirteen arrows. In the eagle’s mouth, it holds a scroll bearing the national motto “E Pluribus Unum” (which, by coincidence, consists of thirteen letters). On the Seal’s reverse, the unfinished pyramid consists of thirteen levels.
- Apollo 13 was a NASA Moon mission famous for being a "successful failure" in 1970.
In rugby league:
- Each side has 13 players on the field at any given time.
- The jersey number 13 is worn by the starting loose forward or lock forward in most competitions. An exception is in the European Super League, which uses static squad numbering.
- In Major League Baseball:
- In the NBA:
- The Charlotte Hornets, for Bobby Phills, who died in a 2000 auto accident while playing for the team. From 2002, when the original Hornets moved to New Orleans (eventually becoming the New Orleans Pelicans), to 2014, when the franchise formerly known as the Charlotte Bobcats reclaimed both the Hornets name and the history of the 1988–2002 Hornets, the number had been honored by the New Orleans franchise.
- The Golden State Warriors, Los Angeles Lakers, and Philadelphia 76ers, all for Hall of Famer Wilt Chamberlain.
- The Portland Trail Blazers, for Dave Twardzik.
- The San Antonio Spurs, for James Silas.
- In the NFL:
- The Toronto Maple Leafs of the NHL have a policy of not retiring numbers unless the number's bearer either died or suffered a career-ending incident while a member of the team. Other players whose numbers would otherwise be retired instead have their numbers enshrined by the team as "Honoured Numbers", which remain in circulation for future players. The number 13 is currently honoured for Hall of Famer Mats Sundin.
In rugby union, the jersey number 13 is worn by one of the two starting centres, usually the outside centre but sometimes the inside centre.
In TV and films
- 13 (musical), a 2007 musical
- 13 (film), an English-language remake of the 2005 French film 13 Tzameti.
- Thirteen (film), a 2003 American film
- Number 13 (film), an uncompleted Hitchcock 1922 film
- 13 Tzameti, a 2005 French film ("Tzameti" means "13" in Georgian)
- 13 Ghosts is a 1960 horror film.
- Thirteen Ghosts a 2001 remake.
- Thirteen is the nickname of Dr. Remy Hadley on the American medical drama House played by Olivia Wilde.
- 13 Assassins is a 2010 film by Japanese director Takashi Miike
- The Thirteen is a 1936 Soviet war film by Mikhail Romm
- The 13th Warrior is a 1999 historical fiction action film starring Antonio Banderas
- District 13 is a 2004 French film (with David Belle)
- Apollo 13 is a 1995 American film.
- 13 (Six Feet Under album) is an album from the American death metal band Six Feet Under.
- In the various incarnations of the television series Battlestar Galactica, the twelve human colonial worlds are destroyed by the mechanical Cylons. The few human survivors then make an interstellar exodus in search of the lost thirteenth colony on a planet called – Earth.
- Warehouse 13 is a television show about the 13th warehouse in the line of warehouses that store supernatural artifacts.
- Friday the 13th is a horror film involving a "monster" called Jason Voorhees.
- Friday the 13th: The Series: Syndicated American-Canadian horror television series, first run 1987 - 1990.
- The 13 Ghosts of Scooby-Doo: Seventh incarnation of the Hanna-Barbera Scooby-Doo cartoon franchise, first run 1985-1986.
- The Thirteenth Floor is a 1999 sci-fi film.
- 13B/Yaavarum Nalam is a 2009 Hindi/Tamil Horror movie starring R Madhavan
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- Frazier, King of the Bean, and the Festival of Fools. Cited in Thompson, Tok. 2002. The thirteenth number: Then, there/ here and now. 'Studia Mythological Slavica 5, 145–159.
- Wells, D. The Penguin Dictionary of Curious and Interesting Numbers, London: Penguin Group. (1987): 67–71.
- de Koninck, J. M. (2009), Those Fascinating Numbers, American Mathematical Society, p. 4, ISBN 9780821886311.
- Rosemary Guiley, The Guinness Encyclopedia of Ghosts and Spirits, 1994, p. 215, ISBN 0-85112-748-7.
- "Most Popular E-mail Newsletter". USA Today. November 24, 2011.
- Fleischman, Sid (August 19, 2007). "The 13th Floor: A Ghost Story". The Washington Post Company. Retrieved July 26, 2008.
- Stan Gooch, Guardians of the Ancient Wisdom (1980)
- "Top 13 Italian Superstitions". Retrieved 2015-08-13.
- "Colgate: History & Traditions". Colgate University. Archived from the original on August 14, 2007. Retrieved September 1, 2007.
- "International Rollergirls' Master Roster".