72 (number)

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72 (seventy-two) is the natural number following 71 and preceding 73. It is half a gross or 6 dozen (i.e., half a "100" in duodecimal).

← 70 71 72 73 74 75 76 77 78 79 → List of numbers — Integers 0 10 20 30 40 50 60 70 80 90 →
Cardinal	72 seventy-two
Ordinal	72nd seventy-second
Factorization
Divisors	1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
Roman numeral	LXXII
Binary	1001000
Duodecimal	60
Hexadecimal	48

Contents 1 In mathematics 2 In science 2.1 In astronomy 3 In religion 4 In other fields

[edit] In mathematics

• Seventy-two is the sum of four consecutive primes (13 + 17 + 19 + 23), as well as the sum of six consecutive primes (5 + 7 + 11 + 13 + 17 + 19). The product of 8 and 9, 72 is a pronic number. And as a multiple of a perfect number, 72 is itself a semiperfect number.
• The sum of Euler's totient function φ(x) over the first fifteen integers is 72. There are 17 solutions to the equation φ(x) = 72, more than any integer below 72, making it a highly totient number.
• The sum of the eighth row of Lozanić's triangle is 72.
• In normal space, the exterior angles of an equilateral pentagon measure 72 degrees each.
• 72 is a Harshad number.

[edit] In science

• The atomic number of hafnium
• In degrees Fahrenheit considered to be room temperature.
• The average number of heartbeats per minute for a resting adult.

[edit] In astronomy

• Messier object M72, a magnitude 10.0 globular cluster in the constellation Aquarius.
• The New General Catalogue object NGC 72, a magnitude 13.5 barred spiral galaxy in the constellation Andromeda.
• The Saros number of the solar eclipse series which began on -727 August 16 and ended on 752 January 21. The duration of Saros series 72 was 1478.1 years, and it contained 83 solar eclipses.
• The Saros number of the lunar eclipse series which began on -407 June 5 and ended on 891 July 25. The duration of Saros series 72 was 1298.1 years, and it contained 73 lunar eclipses.

[edit] In religion

• The conventional number of scholars translating the Septuagint, according to the legendary account in the "Letter of Aristeas".
• The conventional number of disciples sent forth by Jesus in Luke 10 in some manuscripts (seventy in others).
• The number of names of God, according to Kabbalah (see names of God in Judaism).
• The Shemhamphorasch related to the number of the names of God.
• The total number of books in the Holy Bible in the Catholic version if the Book of Lamentations is considered part of the Book of Jeremiah.
• The number of warriors on the Muslim side at the Battle of Badr.
• The number of people martyred along with Imam Hussain at the Battle of Karbala.
• The number of soldiers who will fight alongside Imam Mahdi against the Dajjal, according to Islamic ahadith.

[edit] In other fields

Seventy-two is also:

• The number of hours in 3 days.
• In dpi, the standard resolution of an Apple Macintosh screen.
• The number of the French department Sarthe.
• The designation of USA Interstate 72, a freeway that runs from Missouri to Illinois, East <> West.
• The registry of the U.S. Navy's nuclear aircraft carrier USS Abraham Lincoln (CVN-72), named after U.S. President Abraham Lincoln.
• The designation of the Soviet T-72 tank.
• In the movie The Red Violin, the lot number of the Bussotti red violin at the DuVal auction house.
• The year AD 72, 72 BC, 1972, or any other year ending with "72".
• The Rule of 72 in finance.
• A loud tone of 72hz makes light objects vibrate.
• The number of victories the Chicago Bulls got in the 1995-96 NBA season, which is the NBA record.
• The usual par for an 18 hole golf course, especially those in tournament play.