List of numbers — Integers << 80 81 82 83 84 85 86 87 88 89 >>
Cardinal	eighty
Ordinal	80th (eightieth)
Numeral system	octagesimal
Factorization
Divisors	2, 4, 5, 8, 10, 16, 20, 40
Roman numeral	LXXX
Binary	01010000
Hexadecimal	50

80 is the natural number following 79 and preceding 81. It is a Harshad number.

• Greek numeral: π´
• See wiktionary:eighty to see 80 in other languages.

Eighty is also:

• the atomic number of mercury (Hg)
• the number of units in a fourscore
• the age at which one becomes an octogenarian
• in the title of Around the World in Eighty Days by Jules Verne
• the model number of the computers TRS-80, IBM 80, Sinclair ZX80, and Aster CT-80
• the model number of:
  • T-80, a Soviet tank
  • IAR 80, a Romanian WWII fighter aircraft
  • McDonnell Douglas MD-80, Arado Ar 80, and F-80 Shooting Star
• part of the name of the bands Eighty-D and Eighty Proof Soul
• the age limit for cardinals to vote in papal elections
• the percentage of work done with 20% of the resources according to a "80-20 rule"
• the length of a beach in Western Australia: Eighty Mile Beach
• the length of the Eighty Years' War or Dutch revolt (1568-1648)
• the number of the French department Somme
  
• the designation of Interstate 80, a freeway that runs from California to New Jersey; the European route E80 from Lisbon to Gürbulak
• the standard TCP/IP port number for HTTP connection
• the 80A, 80B and 80C photographic filters correct for excessive redness under tungsten lighting
• The ISBN Group Identifier for books published in the Czech Republic and Slovakia.
• The year AD 80, 80 BC, or 1980.