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80 (number)
Encyclopedia
80 is the natural number
following 79
and preceding 81
.
φ(x) over the first sixteen integers is 80.
Adding up some subsets of its divisors (e.g., 1, 4, 5, 10
, 20
and 40
) gives 80, hence 80 is a semiperfect number
.
80 is a ménage number, and is a Harshad number
number in base 10.
The Pareto principle
(also known as the "80-20 rule," states that, for many events, roughly 80% of the effects come from 20% of the causes.
for cardinals
to vote in papal elections.
wore the number 80 for the majority of his NFL career. The number 80 is also the retired number of Seattle Seahawks
wide receiver Steve Largent
; when Rice was traded to the Seahawks, Largent gave the team permission to unretire his number so Rice could wear it.
Natural number
In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...
following 79
79 (number)
Seventy-nine is the natural number following 78 and preceding 80.79 may represent:-In mathematics:*An odd number*The smallest number that can't be represented as a sum of fewer than 19 fourth powers*A strictly non-palindromic number...
and preceding 81
81 (number)
81 is the natural number following 80 and preceding 82.-In mathematics:Eighty-one is the square of 9 and the fourth power of 3. Like all powers of three, 81 is a perfect totient number. It is a heptagonal number and a centered octagonal number. It is also a tribonacci number, and an open meandric...
.
In mathematics
The sum of Euler's totient functionEuler's totient function
In number theory, the totient \varphi of a positive integer n is defined to be the number of positive integers less than or equal to n that are coprime to n In number theory, the totient \varphi(n) of a positive integer n is defined to be the number of positive integers less than or equal to n that...
φ(x) over the first sixteen integers is 80.
Adding up some subsets of its divisors (e.g., 1, 4, 5, 10
10 (number)
10 is an even natural number following 9 and preceding 11.-In mathematics:Ten is a composite number, its proper divisors being , and...
, 20
20 (number)
20 is the natural number following 19 and preceding 21. A group of twenty units may also be referred to as a score.-In mathematics:*20 is the basis for vigesimal number systems....
and 40
40 (number)
40 is the natural number following 39 and preceding 41.Despite being related to the word "four" , 40 is spelled "forty", and not "fourty"...
) gives 80, hence 80 is a semiperfect number
Semiperfect number
In number theory, a semiperfect number or pseudoperfect number is a natural number n that is equal to the sum of all or some of its proper divisors. A semiperfect number that is equal to the sum of all its proper divisors is a perfect number....
.
80 is a ménage number, and is a Harshad number
Harshad number
A Harshad number, or Niven number in a given number base, is an integer that is divisible by the sum of its digits when written in that base. Harshad numbers were defined by D. R. Kaprekar, a mathematician from India. The word "Harshad" comes from the Sanskrit + , meaning joy-giver. The Niven...
number in base 10.
The Pareto principle
Pareto principle
The Pareto principle states that, for many events, roughly 80% of the effects come from 20% of the causes.Business-management consultant Joseph M...
(also known as the "80-20 rule," states that, for many events, roughly 80% of the effects come from 20% of the causes.
In science
- The atomic numberAtomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
of mercuryMercury (element)Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum... - A rectifierRectifierA rectifier is an electrical device that converts alternating current , which periodically reverses direction, to direct current , which flows in only one direction. The process is known as rectification...
vacuum tubeVacuum tubeIn electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
manufactured from the mid-1920s through the mid-1980s, the longest production run of any American vacuum tube.
In religion
According to Exodus 7:7, Moses was 80 years old when he initially spoke to Pharaoh on behalf of his people. Today, 80 years of age is the upper age limitAgeing
Ageing or aging is the accumulation of changes in a person over time. Ageing in humans refers to a multidimensional process of physical, psychological, and social change. Some dimensions of ageing grow and expand over time, while others decline...
for cardinals
Cardinal (Catholicism)
A cardinal is a senior ecclesiastical official, usually an ordained bishop, and ecclesiastical prince of the Catholic Church. They are collectively known as the College of Cardinals, which as a body elects a new pope. The duties of the cardinals include attending the meetings of the College and...
to vote in papal elections.
In sports
Jerry RiceJerry Rice
Jerry Lee Rice is a retired American football wide receiver. He is generally regarded as the greatest wide receiver of all time and one of the greatest players in National Football League history...
wore the number 80 for the majority of his NFL career. The number 80 is also the retired number of Seattle Seahawks
Seattle Seahawks
The Seattle Seahawks are a professional American football team based in Seattle, Washington. They are currently members of the Western Division of the National Football Conference in the National Football League . The team joined the NFL in 1976 as an expansion team...
wide receiver Steve Largent
Steve Largent
Steven Michael "Steve" Largent is a retired American football player, enshrined in the Pro Football Hall of Fame, and a former U.S. Congressman, having served in the U.S. House of Representatives for Oklahoma from 1994 until 2002...
; when Rice was traded to the Seahawks, Largent gave the team permission to unretire his number so Rice could wear it.
In other fields
Eighty is also:- the length of the Eighty Years' War or Dutch revolt (1568–1648)
- the standard TCP/IP portTCP and UDP portIn computer networking, a port is an application-specific or process-specific software construct serving as a communications endpoint in a computer's host operating system. A port is associated with an IP address of the host, as well as the type of protocol used for communication...
number for HTTP connections - the 80A, 80B and 80C photographic filters correct for excessive redness under tungstenTungstenTungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
lighting - The year AD 8080Year 80 was a leap year starting on Saturday of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Domitianus...
, 80 BC80 BCYear 80 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Sulla and Metellus...
, or 1980 - The highest score possible on each of the three sections of the PSATPSAT/NMSQTThe Preliminary SAT/National Merit Scholarship Qualifying Test is a standardized test administered by the College Board and National Merit Scholarship Corporation in the United States.This test is offered by the College Board....
- Eighty shilling ale
- I-80Interstate 80Interstate 80 is the second-longest Interstate Highway in the United States, following Interstate 90. It is a transcontinental artery running from downtown San Francisco, California to Teaneck, New Jersey in the New York City Metropolitan Area...
is an interstate highway going from New York to San Francisco - The older four-pin-base version of the 5Y3GT rectifierRectifierA rectifier is an electrical device that converts alternating current , which periodically reverses direction, to direct current , which flows in only one direction. The process is known as rectification...
tubeVacuum tubeIn electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum... - A common limit for the characters per lineCharacters per lineIn typography and computing characters per line or terminal width refers to the maximal number of monospaced characters that may appear on a single line...
, in computing, derived from the number of columns in IBM cards - American band Green DayGreen DayGreen Day is an American punk rock band formed in 1987. The band consists of lead vocalist and guitarist Billie Joe Armstrong, bassist and backing vocalist Mike Dirnt, and drummer Tre Cool...
has a song called "80" - A fictional alien superhero named Ultraman 80Ultraman 80is a Japanese tokusatsu TV show produced by Tsuburaya Productions which aired on the Tokyo Broadcasting System channel from April 2, 1980 to March 25, 1981, lasting a total of 50 episodes. It was the ninth TV show in the Ultra Series and began a week after the conclusion of the anime series The...
External links
- wiktionary:eighty for 80 in other languages.