13 (number)


13 is the natural number following 12 and preceding 14.
Strikingly 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. This can be witnessed, for example, in the "Twelve Days of Christmas" of Western European tradition.

In mathematics

The number 13 is:
Since 52 + 122 = 132, forms a Pythagorean triple.
There are 13 Archimedean solids as normally counted, although some include the Elongated square gyrobicupola as a fourteenth.
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

Division12345678910111213141516
13 ÷ x136.54.3.252.62.11.1.6251.1.31.1.0810.90.80.8125
x ÷ 130.0.0.0.0.0.0.0.0.0.0.0.11.1.1.

Exponentiation12345678910111213
131316921972856137129348268096274851781573072110604499373137858491849179216039403723298085122481302875106592253
x''181921594323671088641220703125130606940169688901040754975581388825418658283291000000000000034522712143931106993205379072302875106592253

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 The Duden now calls this tradition outdated and no longer valid, but many writers still follow it.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 religion

Islam

In Shia Islam, 13 signifies the 13th day of the month of Rajab, which is the birth of Imam Ali. 13 also is a total of 1 Prophet and 12 Imams in the Islamic School of Thought. However, in Sunni Islam, the number 13 bears no symbolic significance.

Christianity

The apparitions of the Virgin of Fátima in 1917 were claimed to occur on the 13th day of six consecutive months.
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 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.
The Vaisakhi, which commemorates the creation of "Khalsa" or pure Sikh was celebrated on April 13 for many years.

Judaism

Since beginning of the Nowruz tradition, the 13th day of each new Iranian year is called Sizdah Be-dar, a festival dedicated to pranks and spending time outdoors.

Other

Unlucky 13

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 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.
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.
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 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 Arthurian legend, which was recorded in Medieval texts, King Arthur is resting in Avalon with the twelve greatest knights of the Round Table, totalling 13, and will return when his country is in peril.
The Thirteen Treasures of Britain are a series of magical items listed in late Medieval texts.
The Thirteen Postures of Tai Chi are thirteen postures which are considered to be of fundamental importance in the practice of Tai Chi.
In astronomy there are 13 star constellations in the zodiac ; this can be compared with astrology where there are 12 signs of the zodiac.

Age 13