(Wikipedia) - 80 (number) (Redirected from Eighty)

← 80 81 82 83 84 85 86 87 88 89 → List of numbers — Integers ← 0 10 20 30 40 50 60 70 80 90 → Cardinal eighty Ordinal 80th (eightieth) Factorization 24× 5 Divisors 1, 2, 4, 5, 8, 10, 16, 20, 40, 80 Roman numeral LXXX Binary 10100002 Ternary 22223 Quaternary 11004 Quinary 3105 Senary 2126 Octal 1208 Duodecimal 6812 Hexadecimal 5016 Vigesimal 4020 Base 36 2836 Hebrew פ (Peh)

← 79 | 80 | 81 → |

80 (eighty) is the natural number following 79 and preceding 81.

Contents- 1 In mathematics
- 2 In science
- 3 In religion
- 4 In sports
- 5 In other fields
- 6 References
- 7 External links

The sum of Euler''s totient function 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 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.

In scienceElement 80: Mercury (Hg)- The atomic number of mercury

- 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 limit for cardinals to vote in papal elections.
- According to sayings from Islamic Prophet Muhammad, Prophet Abraham was circumcised when he was 80 years old.

Jerry Rice 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.

In other fieldsEighty is also:

- used in the classic book title Around the World in Eighty Days
- the length of the Eighty Years'' War or Dutch revolt (1568–1648)
- the standard TCP/IP port number for HTTP connections
- the 80A, 80B and 80C photographic filters correct for excessive redness under tungsten lighting
- The year AD 80, 80 BC, or 1980
- Eighty shilling ale
- I-80 is an interstate highway going from New York to San Francisco
- The older four-pin-base version of the 5Y3GT rectifier tube
- A common limit for the characters per line, in computing, derived from the number of columns in IBM cards
- American band Green Day has a song called "80"
- A fictional alien superhero named Ultraman 80

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