# 72 (number)

From HandWiki

__: Natural number__

**Short description**
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Cardinal | seventy-two | |||

Ordinal | 72nd (seventy-second) | |||

Factorization | 2^{3} × 3^{2} | |||

Divisors | 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72 | |||

Greek numeral | ΟΒ´ | |||

Roman numeral | LXXII | |||

Binary | 1001000_{2} | |||

Ternary | 2200_{3} | |||

Quaternary | 1020_{4} | |||

Quinary | 242_{5} | |||

Senary | 200_{6} | |||

Octal | 110_{8} | |||

Duodecimal | 60_{12} | |||

Hexadecimal | 48_{16} | |||

Vigesimal | 3C_{20} | |||

Base 36 | 20_{36} |

**72** (**seventy-two**) is the natural number following 71 and preceding 73. It is half a gross or 6 dozen (i.e., 60 in duodecimal).

## In mathematics

Seventy-two is

- a pronic number, the product of 8 and 9
- 72 is the smallest Achilles number, as a powerful number that is not itself a power
- The sum of Euler's totient function φ(
*x*) over the first fifteen integers - a highly totient number as there are 17 solutions to the equation φ(
*x*) = 72, more than any integer below 72. - the smallest number whose fifth power is the sum of five smaller fifth powers: 19
^{5}+ 43^{5}+ 46^{5}+ 47^{5}+ 67^{5}= 72^{5} - 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 sum of the eighth row of Lozanić's triangle.

- In a plane, the exterior angles of a regular pentagon measure 72 degrees each.

- In base 10, the number 72 is a Harshad number.

- In maths and economics, 72 plays a role in the Rule of 72.

## In science

- The atomic number of hafnium
- In degrees Fahrenheit considered to be room temperature.

### 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 precession of equinoxes traces out a pair of cones joined at their apices in a cycle of approximately 26,000 years, that is 1 degree every 72 years (approximation to the nearmost integer).

## In religion

- The number of languages spoken at the Tower of Babylon, according to later tradition.
- 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 Bible in the Catholic version if the
*Book of Lamentations*is considered part of the*Book of Jeremiah*. - The current distribution of the Book of Revelation is 22 chapters, adopted since the 13th century, but the oldest known division of the text is that of the Greek commentator Andrew of Cesary (6th century) in 72 chapters.
- The number of people martyred along with Imam Hussain at the Battle of Karbala.
- The number of houri each Muslim martyr (or every Muslim male, according to some ahadith) shall receive as companions in Paradise.
- The degrees of the Jacob's Ladder were to the number of 72, according to the Zohar.
- The 72 disciples of Confucius who mastered his teachings (also given as 77).
- Mahavira, the twenty-fourth and last tirthankara of Jainism, is said to have attained nirvana after his physical death at the age of 72.
- Thoth, in an Egyptian creation myth, wins a 72nd of each day of the year from the Moon in a game of draughts, as a favour to Nut, the Sky Goddess. He uses these portions to make the five intercalary days on which the remaining Gods and Goddesses are born.
^{[1]} - The good god Osiris was enclosed in a coffin by 72 evil disciples and accomplices of Set.
^{[2]} - At the age of the puberty, the young Parsee received the investiture of the sacred cord Kucti made of 72 linens in symbol of the community.
- In Cao Đài, the number of planets between hell and heaven.
- There are 72 stupas which comprise Borobudur, the world's largest Buddhist temple.
- 72 major temples have been found at Angkor, seat of the ancient Khmer Empire.
- In Islam, 72 is the number of sects or denominations that are doomed to Hell, according to
*Hadith*(Sayings of prophet Muhammad).^{[3]}^{[4]} - The number of demons sealed away by King Solomon with The Lesser Key of Solomon.

## In other fields

**Seventy-two** is also:

- In dots per inch (dpi), the default screen resolution for an image or graphic on an Apple Macintosh screen.
- In typography, a point is 1/72 inch.
- The number of the French department Sarthe.
- 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.
- The Rule of 72 in finance.
- Book:
*72 Hour Hold*by Bebe Moore Campbell - CD:
*Seventy Two & Sunny*by Uncle Kracker - Jill Clayburgh and LeVar Burton starred in
*Firestorm: 72 Hours in Oakland*(1993) - Alternative music band The Delta 72
- The Persian classical santur, a hammered dulcimer, has 72 strings in 24 triple-stringed courses.
- The Turin Brakes song, also known as Emergency 72
- The number of members in National Senate of Argentina.
- A Civil Air Patrol unit in Laramie, WY, RMR-WY-072.
- There are 72 demons and other spirits in the goetia
*The Lesser Key of Solomon*. - A form of radio shorthand that roughly translates as meaning "Best wishes" in the QRP (low power) community
- A common limit for characters per line in computing
- 72 equal temperament is a tuning used in Byzantine music and by some modern composers.

## In sports and games

- The usual par for an 18-hole golf course, especially those in tournament play.
- The number of victories the Chicago Bulls achieved during the 1995-96 NBA season, which was at the time the National Basketball Association record.
- The number of spaces in a game of Parcheesi, from start space to "home."

## Footnotes

- ↑ ISBN:0-292-72076-9
- ↑ "Egyptian Myths", George Hart, p41, University of Texas Press, 1990
- ↑ "Sects In Islam - 73 Groups in Islam, Division - Denominations". http://www.islamandsects.com.
- ↑ Sunan Ibn Maajah, no. 3982 "My Ummah will be divided into seventy-three sects, one of which will be in Paradise and seventy-two will be in the Fire"

## External links

- Go Figure: What can 72 tell us about life,
*BBC News*, 20 July 2011

Original source: https://en.wikipedia.org/wiki/72 (number).
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