80 ( eighty) is the natural number following 79 and preceding 81.
In mathematics [ edit ]
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.
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. [1 ] [2 ]
Every solvable configuration of
the Fifteen puzzle can be solved in no more than 80 single-tile moves. [3 ]
In science [ edit ]
In religion [ edit ]
In sports [ edit ]
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 fields [ edit ]
Eighty is also:
References [ edit ]
^ Bunkley, Nick (March 3, 2008), "Joseph Juran, 103, Pioneer in Quality Control, Dies", New York Times .
^ What is 80/20 Rule, Pareto’s Law, Pareto Principle .
^ A. Brüngger, A. Marzetta, K. Fukuda and J. Nievergelt, The parallel search bench ZRAM and its applications, Annals of Operations Research 90 (1999), pp. 45–63.
External links [ edit ]