| ||||
---|---|---|---|---|
Cardinal | eighty-four | |||
Ordinal | 84th (eighty-fourth) | |||
Factorization | 01869626685 | |||
Divisors | 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84 | |||
Greek numeral | ΠΔ´ | |||
Roman numeral | LXXXIV | |||
Binary | 10101002 | |||
Ternary | 100103 | |||
Senary | 2206 | |||
Octal | 1248 | |||
Duodecimal | 7012 | |||
Hexadecimal | 5416 |
84 (eighty-four) is the natural number following 83 and preceding 85.
In mathematics
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Hepteract_ortho_petrie.svg/200px-Hepteract_ortho_petrie.svg.png)
84 is a semiperfect number,[1] being thrice a perfect number, and the sum of the sixth pair of twin primes .[2] It is the number of four-digit perfect powers in decimal.[3]
It is the third (or second) dodecahedral number,[4] and the sum of the first seven triangular numbers (1, 3, 6, 10, 15, 21, 28), which makes it the seventh tetrahedral number.[5]
The twenty-second unique prime in decimal, with notably different digits than its preceding (and known following) terms in the same sequence, contains a total of 84 digits.[6]
A hepteract is a seven-dimensional hypercube with 84 penteract 5-faces.[7]
84 is the limit superior of the largest finite subgroup of the mapping class group of a genus surface divided by .[citation needed]
Under Hurwitz's automorphisms theorem, a smooth connected Riemann surface of genus will contain an automorphism group whose order is classically bound to .[8]
84 is the thirtieth and largest for which the cyclotomic field has class number (or unique factorization), preceding 60 (that is the composite index of 84),[9] and 48.[10][11]
There are 84 zero divisors in the 16-dimensional sedenions .[12]
In astronomy
[edit]- Messier object M84, a magnitude 11.0 lenticular galaxy in the constellation Virgo
- The New General Catalogue object NGC 84, a single star in the constellation Andromeda
In other fields
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/22/Vietnam_in_its_region.svg/90px-Vietnam_in_its_region.svg.png)
Eighty-four is also:
- The year AD 84, 84 BC, or 1984.
- The number of years in the Insular latercus, a cycle used in the past by Celtic peoples,[13] equal to 3 cycles of the Julian Calendar and to 4 Metonic cycles and 1 octaeteris
- The atomic number of polonium
- The model number of Harpoon missile
- WGS 84 - The latest revision of the World Geodetic System, a fixed global reference frame for the Earth.
- The house number of 84 Avenue Foch
- The number of the French department Vaucluse
- The code for international direct dial phone calls to Vietnam
- The town of Eighty Four, Pennsylvania
- The company 84 Lumber
- The ISBN Group Identifier for books published in Spain
- A variation of the game 42 played with two sets of dominoes.
- The film 84 Charing Cross Road (1987) starring Anne Bancroft and Anthony Hopkins
- KKNX Radio 84 in Eugene, Oregon
- The B-Side to "Up All Night" (Take That song)
- British Army term for the 84mm Carl Gustav recoilless rifle.
- How many Earth years it takes Uranus to orbit the Sun once
- The total number of Vertcoin to be released is 84 million “Vertcoin”
- The number of former National Football League player Antonio Brown
See also
[edit]References
[edit]- ^ Sloane, N. J. A. (ed.). "Sequence A005835 (Pseudoperfect (or semiperfect) numbers n: some subset of the proper divisors of n sums to n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A077800 (List of twin primes {p, p+2})". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2023-06-08.
- ^ Sloane, N. J. A. (ed.). "Sequence A075308 (Number of n-digit perfect powers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A006566 (Dodecahedral numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000292 (Tetrahedral (or triangular pyramidal) numbers: a(n) = C(n+2,3) = n*(n+1)*(n+2)/6)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A040017 (Prime 3 followed by unique period primes (the period r of 1/p is not shared with any other prime))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2023-06-08.
- ^ Sloane, N. J. A. (ed.). "Sequence A046092 (4 times triangular numbers: a(n) = 2*n*(n+1))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Giulietti, Massimo; Korchmaros, Gabor (2019). "Algebraic curves with many automorphisms". Advances in Mathematics. 349 (9). Amsterdam, NL: Elsevier: 162–211. arXiv:1702.08812. doi:10.1016/J.AIM.2019.04.003. MR 3938850. S2CID 119269948. Zbl 1419.14040.
- ^ Sloane, N. J. A. (ed.). "Sequence A002808 (The composite numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Washington, Lawrence C. (1997). Introduction to Cyclotomic Fields. Graduate Texts in Mathematics. Vol. 83 (2nd ed.). Springer-Verlag. pp. 205–206 (Theorem 11.1). ISBN 0-387-94762-0. MR 1421575. OCLC 34514301. Zbl 0966.11047.
- ^ Sloane, N. J. A. (ed.). "Sequence A005848 (Cyclotomic fields with class number 1 (or with unique factorization))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Cawagas, Raoul E. (2004). "On the Structure and Zero Divisors of the Cayley-Dickson Sedenion Algebra". Discussiones Mathematicae – General Algebra and Applications. 24 (2). PL: University of Zielona Góra: 262–264. doi:10.7151/DMGAA.1088. MR 2151717. S2CID 14752211. Zbl 1102.17001.
- ^ Venerabilis, Beda (May 13, 2020) [731 AD]. "Historia Ecclesiastica gentis Anglorum/Liber Secundus" [The Ecclesiastical History of the English Nation/Second Book]. Wikisource (in Latin). Retrieved September 29, 2022.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction