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Encyclopedia > 80 (number)

80 (eighty) is the natural number following 79 and preceding 81. In mathematics, a natural number can mean either an element of the set {1, 2, 3, ...} (i. ... 79 (seventy-nine) is the natural number following 78 and preceding 80. ... 81 is the natural number following 80 and preceding 82. ...

 ← 80 81 82 83 84 85 86 87 88 89 → 79 (seventy-nine) is the natural number following 78 and preceding 80. ... 81 is the natural number following 80 and preceding 82. ... 82 is the natural number following 81 and preceding 83. ... 83 (eighty-three) is the natural number following 82 and preceding 84. ... 84 (eighty-four) is the natural number following 83 and preceding 85. ... 85 is the natural number following 84 and preceding 86. ... 86 (eighty-six) is the natural number following 85 and preceding 87. ... 87 (eighty-seven) is the natural number following 86 and preceding 88. ... 88 (eighty-eight) is the natural number following 87 and preceding 89. ... 89 (eighty-nine) is the natural number following 88 and preceding 90. ... 90 (ninety) is the natural number preceded by 89 and followed by 91. ... List of numbers — Integers This is a list of articles about numbers (not about numerals). ... The integers are commonly denoted by the above symbol. ... 0 10 20 30 40 50 60 70 80 90 → For other senses of this word, see zero or 0. ... This article is about the number 10. ... 20 (twenty) is the natural number following 19 and preceding 21. ... 30 (thirty) is the natural number following 29 and preceding 31. ... 40 (forty) is the natural number following 39 and preceding 41. ... 50 (fifty) is the number following 49 and preceding 51. ... 60 (sixty) is the natural number following 59 and preceding 61. ... Look up seventy in Wiktionary, the free dictionary. ... 90 (ninety) is the natural number preceded by 89 and followed by 91. ... 100 (one hundred) (the Roman numeral is C for centum) is the natural number following 99 and preceding 101. ... Cardinal 80 eighty Ordinal 80th eightieth Factorization $2^4 cdot 5$ Divisors 1, 2, 4, 5, 8, 10, 16, 20, 40, 80 Roman numeral LXXX Roman numeral (Unicode) LXXX, lxxx Binary 1010000 Octal 120 Duodecimal 68 Hexadecimal 50 Greek numeral π´ Hebrew פ (Pe)
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## Contents

Aleph-0, the smallest infinite cardinal In mathematics, cardinal numbers, or cardinals for short, are a generalized kind of number used to denote the size of a set, known as its cardinality. ... In set theory, ordinal, ordinal number, and transfinite ordinal number refer to a type of number introduced by Georg Cantor in 1897, to accommodate infinite sequences and to classify sets with certain kinds of order structures on them. ... ... In mathematics, a divisor of an integer n, also called a factor of n, is an integer which evenly divides n without leaving a remainder. ... The system of Roman numerals is a numeral system originating in ancient Rome, and was adapted from Etruscan numerals. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7. ... The duodecimal (also known as base-12 or dozenal) system is a numeral system using twelve as its base. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0â€“9 and Aâ€“F, or aâ€“f. ... Greek numerals are a system of representing numbers using letters of the Greek alphabet. ... The Modern Hebrew language is a Semitic language of the Afro-Asiatic language family. ... Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ...

The sum of Euler's totient function φ(x) over the first sixteen integers is 80. The first thousand values of Ï†(n) In number theory, the totient (n) of a positive integer n is defined to be the number of positive integers less than or equal to n and coprime to n. ...

Adding up some subsets of its divisors (e.g., 1, 4, 5, 10, 20 and 40) gives 80, hence 80 is a semiperfect number. In mathematics, 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. ...

80 is a Harshad number number in base 10. A Harshad number, or Niven number, is an integer that is divisible by the sum of its digits in a given number base. ... Decimal, or denary, notation is the most common way of writing the base 10 numeral system, which uses various symbols for ten distinct quantities (0, 1, 2, 3, 4, 5, 6, 7, 8 and 9, called digits) together with the decimal point and the sign symbols + (plus) and &#8722; (minus...

## In other fields

Element 80: Mercury (Hg)

Eighty is also: Image File history File linksMetadata Download high resolution version (1268x1012, 224 KB) Summary Picture I took of a small puddle of the element mercury. ... Image File history File linksMetadata Download high resolution version (1268x1012, 224 KB) Summary Picture I took of a small puddle of the element mercury. ... General Name, Symbol, Number Mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12 (IIB), 6 , d Density, Hardness liquid 13. ...

Results from FactBites:

 80 (number) - Wikipedia, the free encyclopedia (369 words) 80 (eighty) is the natural number following 79 and preceding 81. The Saros number of the solar eclipse series which began on 333 BC June 13 and ended on 929 July 9. Further, the Saros number of the lunar eclipse series which began on 121 BC January 27 and ended on 1213 April 6.
 The View from Number 80 - Skeptical Reviews (8439 words) Number 80 tried to give them critical attention and, in many cases, a certain amount of ridicule. 80 has labelled her a hypocrite (see Damned If You Do) for such a stance as one of the main precepts of Opus Dei is to apply your faith to your work - and now this report confirms she didn't mean a word of it, which makes her a liar and a hypocrite. 80 is willing to bet that gays are far outnumbered by "straights" on this roll of shame - if only for the reason they are outnumbered in the general population.
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