40 (number)

In mathematics

• Forty is a composite number, an octagonal number, and as the sum of the first four pentagonal numbers: 1+5+12+22=40, it is a pentagonal pyramidal number. Adding up some subsets of its divisors gives 40, hence 40 is a semiperfect number.
• Given 40, the Mertens function returns 0. 40 is the smallest number n with exactly 9 solutions to the equation φ = n.
• Forty is the number of n-queens problem solutions for n = 7.
• 40 is a repdigit in base 3 and a Harshad number in base 10.

  In science

• The atomic number of zirconium.
• Negative forty is the unique temperature at which the Fahrenheit and Celsius scales correspond; that is, −40 °F = −40 °C. It is referred to as either "minus forty" or "forty below".

  Astronomy

• Messier object M40, a magnitude 9.0 double star in the constellation Ursa Major
• The New General Catalogue object NGC 40, a magnitude 12.4 planetary nebula in the constellation Cepheus

  In religion

Sumerian

• Enki or Enkil is a god in Sumerian mythology, later known as Ea in Akkadian and Babylonian mythology. He was originally patron god of the city of Eridu, but later the influence of his cult spread throughout Mesopotamia and to the Canaanites, Hittites and Hurrians. He was the deity of crafts ; mischief; water, seawater, lake water, intelligence and creation. He was associated with the southern band of constellations called stars of Ea, but also with the constellation AŠ-IKU, the Field. Beginning around the second millennium BCE, he was sometimes referred to in writing by the numeric ideogram for "40," occasionally referred to as his "sacred number."

Judaism

• In the Hebrew Bible, forty is often used for time periods, forty days or forty years, which separate "two distinct epochs".
• Rain fell for "forty days and forty nights" during the Flood.
• Noah waited for forty days after the tops of mountains were seen after the flood, before releasing a raven.
• Spies were sent by Moses to explore the land of Canaan for "forty days".
• The Hebrew people lived in the lands outside of the promised land for "forty years". This period of years represents the time it takes for a new generation to arise.
• Several early Hebrew leaders and kings are said to have ruled for "forty years", that is, a generation. Examples include Eli, Saul, David, and Solomon.
• Goliath challenged the Israelites twice a day for forty days before David defeated him.
• Moses spent three consecutive periods of "forty days and forty nights" on Mount Sinai:

1. He went up on the seventh day of Sivan, after God gave the Torah to the Jewish people, in order to learn the Torah from God, and came down on the seventeenth day of Tammuz, when he saw the Jews worshiping the Golden Calf and broke the tablets.
2. He went up on the eighteenth day of Tammuz to beg forgiveness for the people's sin and came down without God's atonement on the twenty-ninth day of Av.
3. He went up on the first day of Elul and came down on the tenth day of Tishrei, the first Yom Kippur, with God's atonement.

• A mikvah consists of 40 se'ah of water
• The prophet Elijah had to walk 40 days and 40 nights before arriving at mount Horeb.
• 40 lashes is one of the punishments meted out by the Sanhedrin, though in actual practice only 39 lashes were administered.
• alludes to the same with ties to the prophecy in The Book of Daniel. "For forty years—one year for each of the forty days you explored the land—you will suffer for your sins and know what it is like to have me against you."
• One of the prerequisites for a man to study Kabbalah is that he is forty years old.
• "The registering of these men was carried on cruelly, zealously, assiduously, from the rising of the sun to its going down, and was not brought to an end in forty days".
• Jonah warns Nineveh that "Forty days more, and Nineveh shall be overthrown."

  Christianity

• Before his temptation, Jesus fasted "forty days and forty nights" in the Judean desert.
• Forty days was the period from the resurrection of Jesus to the ascension of Jesus.
• According to Stephen, Moses' life is divided into three 40-year segments, separated by his growing to adulthood, fleeing from Egypt, and his return to lead his people out.
• In modern Christian practice, Lent consists of the 40 days preceding Easter. In much of Western Christianity, Sundays are excluded from the count; in Eastern Christianity, Sundays are included.
• The Forty Martyrs of Sebaste
• Kirk Kilisse, "Forty Churches" in Eastern Thrace
• Rain fell for "forty days and forty nights" during the Flood.

  Islam

• Muhammad was forty years old when he first received the revelation delivered by the archangel Gabriel.
• Masih ad-Dajjal roams around the Earth in forty days, the first day length is like one year, the second day is like one month, the third day is like one week and the next day is like one day.
• God forbade the Israelites from entering the Holy Land for 40 years to separate them from Musa and his brother.
• Musa spent 40 days on Mount Sinai where he received the 10 commandments.

  Yazidism

• In the Yazidi faith, The Chermera Temple is so old that no one remembers how it came to have that name but it is believed to derive from the burial of 40 men on the mountaintop site.

  Funerary customs

• Some Russians and Serbs believe that ghosts of the dead linger at the site of their death for forty days. After the forty days, additional prayers are performed at the grave or panihida ), to escort the soul on its way to God's court.
• Many Christian Filipinos mark the end of the initial mourning period on the fortieth day after death, and have a Mass said. They believe that the soul remains on the earthly plane for forty days before entering the afterlife, recalling how Christ ascended to heaven forty days after his Resurrection.

  Hinduism

• In Hinduism, some popular religious prayers consist of forty shlokas or dohas. The most common being the Hanuman Chalisa.

Sikhism

• Anand Sahib, the fifth and the final of the daily Sikh prayers have 40 paragraphs, and the 40th paragraph is often read when concluding any Sikh ceremony.
• Chali Mukte refer to the 40 soldiers in the army of Guru Gobind Singh. These 40 disciples were the most favorite and beloved disciples of the Guru.

  In entertainment

• "#40" is a song by Dave Matthews Band
• "40" is a song by Franz Ferdinand
• "40" is a 1983 song by U2 from their album War, whose lyrics are a modification of Psalm 40
• Crush 40 is an American-Japanese hard rock band featured in the Sonic the Hedgehog franchise produced by Sega and Sonic Team; their self-titled album is named after the band.
• The highest number counted to on Sesame Street
• The number of positions on several radio countdown programs, notably American Top 40, American Country Countdown, and Rick Dees' Weekly Top 40
• Chefs are given a $40 budget in The Early Show segment "Chef on a Shoestring".
• Noah Shebib, the Canadian hip hop producer is also known as "40".
• "Forty Shades of Green", a song about Ireland, was written and recorded by Johnny Cash in 1961.
• Fortycoats & Co. was an Irish children's television drama series of the 1980s; the name is based on the nickname of a Dublin tramp, Johnny Fortycoats, of the 1930s.

  In sports

• In baseball, each team in Major League Baseball is allowed to have 40 players under major-league contracts at any given time. From September 1 to the end of the regular season, teams were allowed to expand their game-day rosters to include the entire 40-man roster through the 2019 season, but from 2020 teams are only allowed 28 players on their game-day rosters during that period.
• In horse racing, the maximum permitted number of runners in the Grand National is 40.
• The 40-yard dash is an important metric in American football scouting.
• In tennis, the number 40 represents the third point gained in a game. A score of 40-40 is called "deuce", at which time a player must score two consecutive points to win the game.
• In NASCAR, the number of cars that have run each race in the top-level Cup Series since 2016, and the second-level Xfinity Series since 2013.

  In other fields

• in the saying "Life begins at forty"
• in the expression "forty winks", meaning a short sleep
• in the trademark name of the penetrating oil and water-displacing spray WD-40; "WD-40" is an abbreviation of "Water Displacement, 40th formula".
• the caliber of the bullet in a number of firearms cartridges, most notably the.40 S&W.
• the number of years of marriage celebrated by the ruby wedding anniversary
• the code for direct dial international phone calls to Romania
• the number of spaces in a standard Monopoly game board
• the number of thieves in Ali Baba and the Forty Thieves and in Ali Shar and Zumurrud, from Thousand and One Nights
• the customary number of hours in a regular workweek in some Western countries
• the number of weeks for an average term of pregnancy, counting from the woman's last menstrual period
• a 40-ounce bottle of malt liquor, referenced in the song "40oz. to Freedom" by Sublime
• The Tessarakonteres, or 40, the largest ship of antiquity, constructed by Ptolemy IV
• Forty is the only integer whose English name has its letters in alphabetical order.
• Forty Foot, a promontory on the southern tip of Dublin Bay, Ireland, from which people have been swimming in the Irish Sea all year round for some 250 years
• After the Civil War, there were plans to offer freed slaves 40 acres and a mule.
• To understand a people, you must live among them for 40 days. ~Arabic proverb
• Quarantine, the practice of isolation to prevent the spread of epidemic disease, derives from a Venetian dialect of the Italian 'quaranta giorni' meaning 'forty days', the period that ships were required to be isolated before passengers and crew could go ashore during the Black Death.
• To qualify for retirement benefits under Social Security, a person must have earnings for 40 quarters.
• Forty-shilling freeholders, a nickname, given to those who qualified for a franchise, the right to vote, based on their interest in land and/or property with an annual rental value of 40s. Introduced in England in 1430, it applied there and in many associated territories, in various forms, up to 1918.