**85** (**eighty-five**) is the natural number following 84 and preceding 86.

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Cardinal | eighty-five | |||

Ordinal | 85th (eighty-fifth) | |||

Factorization | 5 × 17 | |||

Divisors | 1, 5, 17, 85 | |||

Greek numeral | ΠΕ´ | |||

Roman numeral | LXXXV | |||

Binary | 1010101_{2} | |||

Ternary | 10011_{3} | |||

Quaternary | 1111_{4} | |||

Quinary | 320_{5} | |||

Senary | 221_{6} | |||

Octal | 125_{8} | |||

Duodecimal | 71_{12} | |||

Hexadecimal | 55_{16} | |||

Vigesimal | 45_{20} | |||

Base 36 | 2D_{36} |

## Contents

## In mathematics

**85** is:

- the product of two prime numbers (5 and 17), and is therefore a biprime; specifically, the 24th biprime not counting perfect squares. Together with 86 and 87, it forms the second cluster of three consecutive biprimes.
- an octahedral number.
^{[1]} - a centered triangular number.
^{[2]} - a centered square number.
^{[3]} - a decagonal number.
^{[4]} - the smallest number that can be expressed as a sum of two squares, with all squares greater than 1, in two ways, 85 = 9
^{2}+ 2^{2}= 7^{2}+ 6^{2}.^{[5]} - the length of the hypotenuse of four pythagorean triangles.
- a Smith number in decimal.
^{[6]}

## In astronomy

- Messier object M85 is a magnitude 10.5 lenticular galaxy in the constellation Coma Berenices
- NGC 85 is a galaxy in the constellation Andromeda
- 85 Io is a large main belt asteroid
- 85 Pegasi is a multiple star system in constellation of Pegasus
- 85 Ceti is a variable star in the constellation of Cetus
- 85P/Boethin is a periodic comet

## In titles and names

*Federalist No. 85*, by Alexander Hamilton, the last of*The Federalist Papers*(1788)*The 85 Ways to Tie a Tie*, a book by Thomas Fink and Yong Mao*85 Days: The Last Campaign of Robert Kennedy*a book by Jules Witcover*Live/1975–85*, an album of live recordings by Bruce Springsteen (1986)*80–85*a compilation album by Bad Religion (1991)*Cupid & Psyche 85*, an album by band Scritti Politti (1985)*45/85*was a television documentary on World War II- Minuscule 85, Papyrus 85, Lectionary 85 are early Greek manuscripts of the New Testament
- "85", a 2000 rap single by YoungBloodz, from their album
*Against Da Grain* - 85°C, a Taiwanese coffee store chain.

## In sports

In U.S. college athletics, schools that are members of NCAA Division I are limited to providing athletic scholarships to a maximum of 85 football players in a given season. The specifics vary by the two Division I football subdivisions:

- In the top-level FBS, each player provided with a scholarship may, and almost always does, receive a full scholarship.
- In the second-level FCS, schools are allowed to provide football-related athletic aid equivalent to 63 full scholarships, but this aid may be divided among up to 85 players as the schools see fit.

## In other fields

- The year AD 85, 85 BC, or 1985.
- The Muslim calendar year 85 AH.
- The atomic number of astatine
- The number of the French department Vendée
- The ISBN Group Identifier for books published in Brazil
- The radix of the Ascii85 (sometimes called Base85) binary-to-text encoding
- The IQ and nickname of Aaron in Alien 3
- The number worn by Chad Ochocinco, whose name means "eight five" in Spanish
- Arabigere 85 is a village in India
- E85 fuel is 85% ethanol and 15% conventional gasoline
- MCS-85 was a family of Intel processors including the 8085
- TI-85 was a graphing pocket calculator by Texas Instruments
- KC 85 was a family of small computers built in East Germany in the 1980s
- PMD 85 was a personal computer built in Czechoslovakia in 1985
- Learjet 85 is an all-composite plane being developed by Bombardier Aerospace
- British Rail Class 85, a category of UK train locomotives
- DRG Class 85, a category of German train locomotives
- TK85 was a clone of the Sinclair ZX81 made in Brazil in 1983
- Lima Site 85 was a battle in the Vietnam War
- A85 is the Dutch Defence in the
*Encyclopaedia of Chess* - EF 85mm is a photographic camera lens by Canon
- F85 (disambiguation), multiple uses
- Part of the assignation for the Toyota AE85, commonly referred to as an "eight-five".

## In military technology

- 85mm is a common caliber for cannons
- SU-85 was a Soviet tank
- TR-85 was a Romanian battle tank
- Tu-85 was a prototype Soviet bomber
- ASU-85 a Soviet self-propelled gun
- CZ 85 is a Czech 9mm semiautomatic pistol
- PT-85 is a Korean tank
- 7.62 Tkiv 85 is a Finnish army rifle
- HG 85 is a Swiss fragmentation grenade
- Taurus Model 85, a 9mm revolver made in Brazil

## See also

- List of highways numbered 85
- List of highways numbered 85A
- Type 85, a designation of many military equipment

## References

**^**"Sloane's A005900 : Octahedral numbers".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-29.**^**"Sloane's A005448 : Centered triangular numbers".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-29.**^**"Sloane's A001844 : Centered square numbers".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-29.**^**"Sloane's A001107 : 10-gonal (or decagonal) numbers".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-29.**^**Sloane, N. J. A. (ed.). "Sequence A007692".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.. Note that the two smaller numbers on this list, 50 and 65, have 1 as one of the squares in their representations as sums of two squares.**^**"Sloane's A006753 : Smith numbers".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-29.

## External links

Wikimedia Commons has media related to .85 (number) |

- 85
- Jorge Stolfi, The Hollywood Constant.