In mathematics[edit]

In science[edit]

• 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[edit]

• The planet Venus forms a pentagram in the night sky every eight years with it returning to its original point every 40 years with a 40 day regression (some scholars believe that this ancient information was the basis for the number 40 becoming sacred to Jews, Christians, and Muslims).^{[citation needed]}
• 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
• The Saros number of the
  • solar eclipse series which began on -1653 May 28 and ended on -373 July 4. The duration of Saros series 40 was 1280.1 years, and it contained 72 solar eclipses.
  • lunar eclipse series which began on -1387 February 12 and ended on -71 April 12. The duration of Saros series 40 was 1316.2 years, and it contained 74 lunar eclipses.

In religion[edit]

Judaism[edit]

• Rain fell for "forty days and forty nights" during the Flood. (Genesis 7:4)
• Spies explored the land of Israel for "forty days." (Numbers 13:25)
• The Hebrew people lived in the Sinai desert for "forty years". This period of years represents the time it takes for a new generation to arise. (Numbers 32:13)
• 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. (Acts 7:23,30,36)
• Several Jewish leaders and kings are said to have ruled for "forty years", that is, a generation. Examples include Eli (1 Samuel 4:18), Saul (Acts 13:21), David (2 Samuel 5:4), and Solomon (1 Kings 11:42).
• Goliath challenged the Israelites twice a day for forty days before David defeated him. (1 Samuel 17:16)
• 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. (Deuteronomy 9:11)
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. (Deuteronomy 9:25)
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. (Deuteronomy 10:10)

• A mikvah consists of 40 se'ah (approximately 200 gallons) of water
• 40 lashes is one of the punishments meted out by the Sanhedrin, though in actual practice only 39 lashes were administered.^[2]
• One of the prerequisites for a man to study Kabbalah is that he is forty years old.

Christianity[edit]

• Before his temptation, Jesus fasted "forty days and forty nights" in the Judean desert. (Matthew 4:2, Mark 1:13, Luke 4:2)
• Forty days was the period from the resurrection of Jesus to the ascension of Jesus. (Acts 1:3)
• Biblical verse Numbers 14:24 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.'"
• 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" (Σαράντα Εκκλησιές) in Eastern Thrace

Islam[edit]

• 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, a period of time that can be as many as forty months, forty years, and so on.
• God forbade the Fasiqun (the non-believers) from entering the Holy Land for 40 years to separate them from Musa (Moses) and his brother.^[3]
• Musa (Moses) spent 40 days on Mount Sinai where he received the 10 commandments.^[4]
• Prophet Ibrahim spent 40 days in a fire and lived because God made the fire like flowers.^{[citation needed]}
• On the 40th verse (ayat) of the 2nd chapter of the Quran (Al-Baqarah) God changes the topic.
• Forty was the number of days that Prophet Ilyas (Elijah) spent in the wilderness before the angel appeared to him with God's message on Mount Horeb.^{[citation needed]}
• Forty was the number of days that Prophet Isa (Jesus) was tempted in the desert by Satan.^{[citation needed]}
• Muhammad praying and fasting in the cave for 40 days.^{[citation needed]}
• Muhammad then had 40 followers to spread the religion of Islam.^{[citation needed]}
• Prophets Dawuud and Suleiman each ruled for forty years.^{[citation needed]}
• Regarding the flood that Noah encountered, it is said that for forty days water continued to pour from the heavens and to stream out over the earth.^{[citation needed]}
• There is also a hadith from Mohammad that the prayers of a person who gossips would not be accepted for forty days and nights. (Al-Kafi, Vol. 6, p. 400)
• Imam Ali has narrated from Mohammad that one who memorizes and preserves forty hadith relating to their religious needs shall be raised by God as a learned scholar on the Day of Resurrection.^{[citation needed]}
• It is said that a person’s intellect attains maturity in forty years, everyone according to his own capacity.^[5]
• It is believed that one who assists a blind man for forty steps becomes worthy of entering heaven.^{[citation needed]}
• Imam Baghir has said: “The prayers of someone who drinks wine are not accepted for forty days.”^{[citation needed]}
• Believers have also been encouraged to devote themselves to God Almighty for forty days to see the springs of wisdom break forth from their hearts and flow from their tongues.^{[citation needed]}
• Mourning period officially last for 40 days.^{[citation needed]}

Yazidism[edit]

• In the Yazidi faith, The Chermera Temple (meaning “40 Men” in the Yazidi dialect) 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[edit]

• Some Russians believe that ghosts of the dead linger at the site of their death for forty days.
• 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[edit]

• In Hinduism, some popular religious prayers consist of forty shlokas or dohas (couplets, stanzas). The most common being theHanuman Chalisa (chaalis is the Hindi term for 40).

Sumerian= Meem = Water = 40

• Enki ( /ˈɛŋki/) or Enkil (Sumerian: dEN.KI(G)𒂗𒆠) 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 (gašam); mischief; water, seawater, lakewater (a, aba, ab), intelligence (gestú, literally "ear") and creation (Nudimmud: nu, likeness, dim mud, make bear). He was associated with the southern band of constellations called stars of Ea, but also with the constellation AŠ-IKU, the Field (Square of Pegasus). 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."