| ||||
---|---|---|---|---|
Cardinal | thirteen | |||
Ordinal | 13th (thirteenth) | |||
Numeral system | tredecimal | |||
Factorization | prime | |||
Prime | 6th | |||
Divisors | 1, 13 | |||
Greek numeral | ΙΓ´ | |||
Roman numeral | XIII, xiii | |||
Binary | 11012 | |||
Ternary | 1113 | |||
Senary | 216 | |||
Octal | 158 | |||
Duodecimal | 1112 | |||
Hexadecimal | D16 | |||
Hebrew numeral | י"ג | |||
Babylonian numeral | 𒌋𒐗 |
13 (thirteen) 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 (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]
The number 13 is a prime number, happy number [2] and a lucky number. [3] 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.
Multiplication | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 50 | 100 | 1000 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
(13)x | 13 | 26 | 39 | 52 | 65 | 78 | 91 | 104 | 117 | 130 | 143 | 156 | 169 | 182 | 195 | 208 | 221 | 234 | 247 | 260 | 273 | 286 | 299 | 312 | 325 | 650 | 1300 | 13000 |
Division | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
13 ÷ x | 13 | 6.5 | 4.3 | 3.25 | 2.6 | 2.16 | 1.857142 | 1.625 | 1.4 | 1.3 | 1.18 | 1.083 | 1 | 0.9285714 | 0.86 |
x ÷ 13 | 0.076923 | 0.153846 | 0.230769 | 0.307692 | 0.384615 | 0.461538 | 0.538461 | 0.615384 | 0.692307 | 0.769230 | 0.846153 | 0.923076 | 1 | 1.076923 | 1.153846 |
Exponentiation | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
---|---|---|---|---|---|---|---|---|---|---|---|
13x | 13 | 169 | 2197 | 28561 | 371293 | 4826809 | 62748517 | 815730721 | 10604499373 | 137858491849 | 1792160394037 |
x13 | 1 | 8192 | 1594323 | 67108864 | 1220703125 | 13060694016 | 96889010407 | 549755813888 | 2541865828329 | 10000000000000 | 34522712143931 |
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. [4]
Thirteen is one of two numbers within the teen numerical range (13–19), along with fifteen, not derived by cardinal numeral (three) and the teen suffix; instead, it is derived from the ordinal numeral (third).
In Shia, 13 signifies the 13th day of the month of Rajab (the Lunar calendar), which is the birth of Imam Ali.
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 [5] 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. [6]
According to famous Sakhi (evidence) 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.
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. [7]
The number 13 is considered an unlucky number in some countries. [8] The end of the Mayan calendar's 13th Baktun was superstitiously feared as a harbinger of the apocalyptic 2012 phenomenon. [9] Fear of the number 13 has a specifically recognized phobia, triskaidekaphobia, a word first recorded in 1911. [10] 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 (thirteenth floor). [11] It is also considered unlucky to have thirteen guests at a table. Friday the 13th has been considered an unlucky day. [8]
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. [8]
A baker's dozen, devil's dozen, [21] 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. [22]
In a tarot card deck, XIII is the card of Death, usually picturing the Pale Horse with its rider.
This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: This coverage of 13 in American heraldry must be shortened. It should be treated as no more or less important than the religious content. All of this non-math content must be strictly focused on the meaning of the number to these groups.(January 2025) |
This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: A lot of the content of this section really belongs under the luck section.(January 2025) |
The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon. This means that the lunar hemisphere facing Earth—the near side—is completely sunlit and appears as an approximately circular disk. The full moon occurs roughly once a month.
The Metonic cycle or enneadecaeteris is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recurrence is not perfect, and by precise observation the Metonic cycle defined as 235 synodic months is just 2 hours, 4 minutes and 58 seconds longer than 19 tropical years. Meton of Athens, in the 5th century BC, judged the cycle to be a whole number of days, 6,940. Using these whole numbers facilitates the construction of a lunisolar calendar.
The Roman calendar was the calendar used by the Roman Kingdom and Roman Republic. Although the term is primarily used for Rome's pre-Julian calendars, it is often used inclusively of the Julian calendar established by Julius Caesar in 46 BC.
Triskaidekaphobia is fear or avoidance of the number 13. It is also a reason for the fear of Friday the 13th, called paraskevidekatriaphobia or friggatriskaidekaphobia.
Friday the 13th is considered an unlucky day in Western superstition. It occurs when the 13th day of the month in the Gregorian calendar falls on a Friday, which happens at least once every year but can occur up to three times in the same year. Common years that begin in Thursday have three Friday the 13ths in February, March, and November, such as 2009, 2015, and 2026. Leap years that begin on Sunday such as 2012 and 2040, also have three Friday the 13ths in January, April, and July. The years 2001, 2002, 2004, 2006, 2007, 2013, 2017, 2018, 2019, 2020, 2023 and 2024 had two Friday the 13ths, as will 2029; 2003, 2005, 2008, 2010, 2011, 2014, 2016, 2021, and 2022 had only one Friday the 13th, as will 2025, 2027, and 2028.
The ancient Egyptian calendar – a civil calendar – was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of five epagomenal days treated as outside of the year proper. Each season was divided into four months of 30 days. These twelve months were initially numbered within each season but came to also be known by the names of their principal festivals. Each month was divided into three 10-day periods known as decans or decades. It has been suggested that during the Nineteenth Dynasty and the Twentieth Dynasty the last two days of each decan were usually treated as a kind of weekend for the royal craftsmen, with royal artisans free from work.
12 (twelve) is the natural number following 11 and preceding 13.
The history of calendars covers practices with ancient roots as people created and used various methods to keep track of days and larger divisions of time. Calendars commonly serve both cultural and practical purposes and are often connected to astronomy and agriculture.
A blue moon refers either to the presence of a second full moon in a calendar month, to the third full moon in a season containing four, or to a moon that appears blue due to atmospheric effects.
48 (forty-eight) is the natural number following 47 and preceding 49. It is one third of a gross, or four dozens.
The calendrical systems devised and used by the pre-Columbian cultures of Mesoamerica, primarily a 260-day year, were used in religious observances and social rituals, such as divination.
The Buddhist calendar is a set of lunisolar calendars primarily used in Tibet, Cambodia, Laos, Myanmar, Bangladesh, India, Sri Lanka, Thailand and Vietnam as well as in Malaysia and Singapore and by Chinese populations for religious or official occasions. While the calendars share a common lineage, they also have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a year numbering system shared by the traditional Thai lunar calendar and by the Thai solar calendar.
The Tibetan calendar, or the Phukpa calendar, known as the Tibetan lunar calendar, is a lunisolar calendar composed of either 12 or 13 lunar months, each beginning and ending with a new moon. A thirteenth month is added every two or three years, so that an average Tibetan year is equal to the solar year. The 15th century Phukpa calendar is the main Tibetan calendar, and the Karma Kagyu's Tsurluk calendar is also in current use. The Tibetan New Year celebration is Losar, which falls either in the months of February or March in the Gregorian calendar.
Often called lunar mansion, a lunar station or lunar house is a segment of the ecliptic through which the Moon passes in its orbit around the Earth. The concept was used by several ancient cultures as part of their calendrical system.
An ecclesiastical full moon is formally the 14th day of the ecclesiastical lunar month in an ecclesiastical lunar calendar. The ecclesiastical lunar calendar spans the year with lunar months of 30 and 29 days which are intended to approximate the observed phases of the Moon. Since a true synodic month has a length that can vary from about 29.27 to 29.83 days, the moment of astronomical opposition tends to be roughly 14.75 days after the previous conjunction of the Sun and Moon. The ecclesiastical full moons of the Gregorian lunar calendar tend to agree with the dates of astronomical opposition, referred to a day beginning at midnight at 0 degrees longitude, to within a day or so. However, the astronomical opposition happens at a single moment for the entire Earth: The hour and day at which the opposition is measured as having taken place will vary with longitude. In the ecclesiastical calendar, the 14th day of the lunar month, reckoned in local time, is considered the day of the full moon at each longitude.
Yakudoshi (厄年), or "calamitous years," are ages that in Japan are traditionally believed to be unlucky.
Numerophobia, arithmophobia, or mathematics anxiety is an anxiety disorder, involving fear of dealing with numbers or mathematics. Sometimes numerophobia refers to fear of particular numbers. Some people with this condition may be afraid of even numbers, odd numbers, unlucky numbers, and/or lucky numbers. Those with this phobia may have a hard time holding certain jobs, paying bills, or managing a budget.