72 (number)
From Wikipedia, the free encyclopedia
72 (seventy-two) is the natural number following 71 and preceding 73. It is half a gross or 6 dozens (i.e., half a "100" in duodecimal).
| 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 |
[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.
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.
- The number of hours in three days.
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 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 heavenly virgins (Hour Al-Aeen) Muslim martyrs are promised to get in heaven by their recruiters.
[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.
- 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, or 1972.
- The Rule of 72 in finance.
- A loud tone of 72hz makes light objects vibrate.
- The Shemhamphorasch related to the number of the names of God.
- The number of victories the Chicago Bulls got in the 1995-96 NBA season, which is the NBA record.
