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# Orders of magnitude (numbers)  The logarithmic scale can compactly represent the relationship among variously sized numbers.

This list contains selected positive numbers in increasing order, including counts of things, dimensionless quantity and probabilities. Each number is given a name in the short scale, which is used in English speaking countries, as well as a name in the long scale, which is used in some of the countries that do not have English as their national language.

## Smaller than 10−100 (one googolth)

• Mathematics — Writing: Approximately 10−183,800 is a rough first estimate of the probability that a monkey, placed in front of a typewriter and given adequate food, breaks, and sleep while doing so, will type all the letters of Hamlet on the first try. However, taking punctuation, capitalization, and spacing into account, the actual probability of the monkey typing Hamlet is less: around 10−360,783.
• Computing: The number 5×10−324 is approximately equal to the smallest positive non-zero value that can be represented by a double-precision IEEE floating-point value.

## 10−100 to 10−30

• Computing: The number 1.4×10−45 is approximately equal to the smallest positive non-zero value that can be represented by a single-precision IEEE floating-point value.

## 10−30

(0.000000000000000000000000000001; 1000−10; short scale: one nonillionth; long scale: one quintillionth)

• Mathematics: The probability in a game of bridge of all four players getting a complete suit is approximately 4.47×10−28.

## 10−27

(0.000000000000000000000000001; 1000−9; short scale: one octillionth; long scale: one quadrilliardth)

## 10−24

(0.000000000000000000000001; 1000−8; short scale: one septillionth; long scale: one quadrillionth)

ISO: yocto- (y)

## 10−21

(0.000000000000000000001; 1000−7; short scale: one sextillionth; long scale: one trilliardth)

ISO: zepto- (z)

• Mathematics: The probability of matching 20 numbers for 20 in a game of Keno is approximately 2.83 × 10−19.

## 10−18

(0.000000000000000001; 1000−6; short scale: one quintillionth; long scale: one trillionth)

ISO: atto- (a)

• Mathematics: The probability of rolling snake eyes 10 times in a row on a pair of fair dice is about 2.74×10−16

## 10−15

(0.000000000000001; 1000−5; short scale: one quadrillionth; long scale: one billiardth)

ISO: femto- (f)

## 10−12

(0.000000000001; 1000−4; short scale: one trillionth; long scale: one billionth)

ISO: pico- (p)

## 10−9

(0.000000001; 1000−3; short scale: one billionth; long scale: one milliardth)

ISO: nano- (n)

• Mathematics — Lottery: The odds of winning the Grand Prize (matching all 6 numbers) in the US Powerball lottery, with a single ticket, under the rules as of August 2009, are 195,249,053 to 1 against, for a probability of 5.12×10−9 (0.000000512%).
• Mathematics — Lottery: The odds of winning the Jackpot (matching the 6 main numbers) in the UK National Lottery, with a single ticket, under the rules as of August 2009, are 13,983,815 to 1 against, for a probability of 7.15×10−8 (0.00000715%).

## 10−6

(0.000001; 1000−2; long and short scales: one millionth)

ISO: micro- (μ)

• Mathematics – Poker: The odds of being dealt a royal flush in poker are 649,739 to 1 against, for a probability of 1.5 × 10−6 (0.00015%).
• Mathematics — Poker: The odds of being dealt a straight flush (other than a royal flush) in poker are 72,192 to 1 against, for a probability of 1.4 × 10−5 (0.0014%).
• Mathematics — Poker: The odds of being dealt a four of a kind in poker are 4,164 to 1 against, for a probability of 2.4 × 10−4 (0.024%).

## 10−3

(0.001; 1000−1; one thousandth)

ISO: milli- (m)

• Mathematics — Poker: The odds of being dealt a full house in poker are 693 to 1 against, for a probability of 1.4 × 10−3 (0.14%).
• Mathematics — Poker: The odds of being dealt a flush in poker are 507.8 to 1 against, for a probability of 1.9 × 10−3 (0.19%).
• Mathematics — Poker: The odds of being dealt a straight in poker are 253.8 to 1 against, for a probability of 4 × 10−3 (0.39%).
• Physics: α = 0.007297352570(5), the fine-structure constant.

## 10−2

(0.01; one hundredth)

ISO: centi- (c)

• Mathematics — Lottery: The odds of winning any prize in the UK National Lottery, with a single ticket, under the rules as of 2003, are 54 to 1 against, for a probability of about 0.018 (1.8%)
• Mathematics — Poker: The odds of being dealt a three of a kind in poker are 46 to 1 against, for a probability of 0.021 (2.1%)
• Mathematics — Lottery: The odds of winning any prize in the US Powerball Multistate Lottery, with a single ticket, under the rules as of 2006, are 36.61 to 1 against, for a probability of 0.027 (2.7%)
• Mathematics — Poker: The odds of being dealt two pair in poker are 20 to 1 against, for a probability of 0.048 (4.8%).

## 10−1

(0.1; one tenth)

ISO: deci- (d)

• Mathematics — Poker: The odds of being dealt only one pair in poker are about 5 to 2 against (2.37 to 1), for a probability of 0.42 (42%).
• Mathematics — Poker: The odds of being dealt no pair in poker are nearly 1 to 2, for a probability of about 0.5 (50%)
• Legal history: 10% was widespread as the tax raised for income or produce in the ancient and medieval period, see tithe.

(1; one)

(10; ten)

ISO: deca- (da)

## 102

(100; hundred)

ISO: hecto- (h)

• European history: Groupings of 100 homesteads was a common administrative unit in Northern Europe and Great Britain, see Hundred (county subdivision)
• Computing: There are 128 characters in the ASCII character set.
• Phonology: The Taa language is estimated to have between 130 and 164 distinct phonemes
• Political Science: There were 193 member states of the United Nations as of 2011.

## 103

(1000; thousand)

ISO: kilo- (k)

• Typesetting: 2,000–3,000 letters on a typical typed page of text.
• Military history: 4,200 (Republic) or 5,200 (Empire) was the standard size of a Roman legion
• BioMed: the DNA of the simplest viruses has some 5,000 base pairs.
• Linguistics: Estimates for the linguistic diversity of living human languages or dialects range between 5,000 and 10,000 (SIL Ethnologue in 2007 listed 6,912 known living languages).
• Lexicography: 8,674 unique words in the Hebrew Bible

## 104

(10000; ten thousand or a myriad)

• BioMed: Each neuron in the human brain is estimated to connect to 10,000 others
• Lexicography: 14,500 unique English words occur in the King James Version of the Bible
• Language: There are 20,000–40,000 distinct Chinese characters, depending on how one counts them
• BioMed: Each human being is estimated to have 30,000 to 40,000 genes
• Mathematics: 65,537 is the largest known Fermat prime
• Memory: As of 2006, the largest number of decimal places of π that have been recited from memory is 67,890

## 105

(100000; one hundred thousand or a lakh)

## 106

(1000000; 10002; long and short scales: one million)

ISO: mega- (M)

• BioMed — Species: The World Resources Institute claims that approximately 1.4 million species have been named, out of an unknown number of total species (estimates range between 2 and 100 million species)
• Info: The freedb database of CD track listings has around 1,750,000 entries as of June 2005
• Mathematics — Playing cards: There are 2,598,960 different 5-card poker hands that can be dealt from a standard 52-card deck.
• Info — Web sites: As of November 2010, Wikipedia contains approximately 3,488,000 articles in the English language
• Geography/Computing — Geographic places: The NIMA GEOnet Names Server contains approximately 3.88 million named geographic features outside the United States, with 5.34 million names. The USGS Geographic Names Information System claims to have almost 2 million physical and cultural geographic features within the United States.
• Genocide: Approximately 5,100,000–6,200,000 Jews were killed in the Holocaust.

## 107

(10000000; a crore; long and short scales: ten million)

• Mathematics: 12,988,816 is the number of domino tilings of an 8×8 checkerboard.
• Computing: 16,777,216 different colors can be generated using the hex code system in HTML (It has been estimated that the trichromatic color vision of the human eye can only distinguish about 1,000,000 different colors.).
• Science Fiction: In Isaac Asimov's Galactic Empire, in what we call 22,500 CE there are 25,000,000 different inhabited planets in the Galactic Empire, all inhabited by humans in Asimov's "human galaxy" scenario.

## 108

(100000000; long and short scales: one hundred million)

## 109

(1000000000; 10003; short scale: one billion; long scale: one thousand million, or one milliard)

ISO: giga- (G)

• Demographics — India: 1,096,000,000 – approximate population of India in 2007
• Demographics — China: 1,311,000,000 – approximate population of the People's Republic of China in 2007.
• Computing — Computational limit of a 32-bit CPU: 2 147 483 647 is equal to 231−1, and as such is the largest number which can fit into a signed (two's complement) 32-bit integer on a computer, thus marking the upper computational limit of a 32-bit CPU such as Intel's Pentium-class computer chips.
• BioMed — base pairs in the genome: approximately 3×109 base pairs in the human genome
• Linguistics: 3,400,000,000 – the total number of speakers of Indo-European languages, of which 2,400,000,000 are native speakers; the other 1,000,000,000 speak Indo-European languages as a second language
• Computing – IPv4: 4,294,967,296 (232) possible unique IP addresses.
• Computing: 4,294,967,296 – the number of bytes in 4 gibibytes; in computation, the 32-bit computers can directly access 232 pieces of address space, this leads directly to the 4 gigabyte limit on main memory.
• Mathematics: 4,294,967,297 is a Fermat number and semiprime. It is the smallest number of the form $2^{2^n}+1$ which is not a prime number.
• Demographics — world population: 7,000,000,000 – Estimated population for the world on 31 October 2011, the Day of Seven Billion.

## 1010

(10000000000; short scale: ten billion; long scale: ten thousand million, or ten milliard)

• BioMed — bacteria in the human body: There are roughly 1010 bacteria in the human oral cavity
• Astronomy — Observable galaxies: as of 2003 there are between 1×1010 and 8×1010 galaxies in the observable universe
• Computing — web pages: approximately 5.6×1010 web pages indexed by Google as of 2010.

## 1011

(100000000000; short scale: one hundred billion; long scale: hundred thousand million, or hundred milliard)

• BioMed — Neurons in the brain: approximately 1011 neurons in the human brain
• Paleodemography: approximately 1.06 × 1011 individuals of Homo sapiens have lived since speciation (40% of this figure are babies who did not live beyond their first year) (see world population).
• Astronomy — stars in our galaxy: approximately 4×1011 stars in the Milky Way galaxy (Often the figure 1×1011 is quoted in error; that is the total mass of the galaxy in solar masses. However, the total number of stars in the galaxy is 4×1011 because 73% of the stars in the galaxy are red dwarves, which have a much smaller mass than the Sun.)

## 1012

(1000000000000; 10004; short scale: one trillion; long scale: one billion)

ISO: tera- (T)

• Astronomy: Andromeda Galaxy, which is part of the same Local Group as our galaxy, contains about 1012 stars.
• BioMed — Bacteria on the human body: The surface of the human body houses roughly 1012 bacteria.
• Marine biology: 3,500,000,000,000 (3.5 × 1012) – estimated population of fish in the ocean.
• Mathematics — Known digits of π: As of 2010, the number of known digits of π is 5,000,000,000,000 (5×1012).
• Mathematics: 7,625,597,484,987 – a number that often appears when dealing with powers of 3. It can be expressed as 196833, 279, 327, $3^{3^3}$ and 33 or when using Knuth's up-arrow notation it can be expressed as $3 \uparrow\uparrow 3$ and $3 \uparrow\uparrow\uparrow 2$.
• Mathematics: 1013 – The approximate number of known non-trivial zeros of the Riemann zeta function as of 2004.
• BioMed — Cells in the human body: The human body consists of roughly 1014 cells, of which only 1013 are human. The remaining 90% non-human cells (though much smaller and constituting much less mass) are bacteria, which mostly reside in the gastrointestinal tract, although the skin is also covered in bacteria.
• Computing – MAC-48: 281,474,976,710,656 (248) possible unique physical addresses.
• Mathematics: 953,467,954,114,363 is the largest known Motzkin prime.

## 1015

(1000000000000000; 10005; short scale: one quadrillion; long scale: one thousand billion, or one billiard)

ISO: peta- (P)

• BioMed-Insects: 1,000,000,000,000,000 to 10,000,000,000,000,000 (1015 to 1016) – The estimated total number of ants on Earth alive at any one time (their biomass is approximately equal to the total biomass of the human race).
• Computing: 9,007,199,254,740,992 (253) – number until which all integer values can exactly be represented in IEEE double precision floating-point format.
• Mathematics: 48,988,659,276,962,496 is the fifth taxicab number.
• Science Fiction: In Isaac Asimov's Galactic Empire, in what we call 22,500 CE there are 25,000,000 different inhabited planets in the Galactic Empire, all inhabited by humans in Asimov's "human galaxy" scenario, each with an average population of 2,000,000,000, thus yielding a total Galactic Empire population of approximately 50,000,000,000,000,000.
• Cryptography: There are 7.205759×1016 different possible keys in the obsolete 56 bit DES symmetric cipher.

## 1018

(1000000000000000000; 10006; short scale: one quintillion; long scale: one trillion)

ISO: exa- (E)

• Computing — Manufacturing: An estimated 6×1018 transistors were produced worldwide in 2008.
• Computing — Computational limit of a 64-bit CPU: 9,223,372,036,854,775,807 (about 9.22×1018) is equal to 263-1, and as such is the largest number which can fit into a signed (two's complement) 64-bit integer on a computer.
• Mathematics — NCAA Basketball Tournament: There are 9,223,372,036,854,775,808 (263) possible ways to enter the bracket.
• Mathematics — Bases: 9,439,829,801,208,141,318 is the 10th and largest number with more than one digit that can be written from base 2 to base 18 using only the digits 0 to 9.
• BioMed — Insects: It has been estimated that the insect population of the Earth is about 1019.
• Mathematics — Answer to the wheat and chessboard problem: When doubling the grains of wheat on each successive square of a chessboard, beginning with one grain of wheat on the first square, the final number of grains of wheat on all 64 squares of the chessboard when added up is 264−1 = 18,446,744,073,709,551,615.
• Mathematics — Legends: In the legend called the Tower of Brahma about a Hindu temple which contains a large room with three posts on one of which is 64 golden discs, the object of the mathematical game is for the Brahmins in the temple to move all of the discs to another pole so that they are in the same order, never placing a larger disc above a smaller disc. It would take 264−1 = 18,446,744,073,709,551,615 turns to complete the task (same number as the wheat and chessboard problem above).
• Mathematics — Rubik's Cube: There are 43,252,003,274,489,856,000 (about 43×1018) different positions of a 3x3x3 Rubik's Cube
• Password strength: Usage of the 95-character set found on standard computer keyboards for a 10-character password yields a computationally intractable 59,873,693,923,837,890,625 (9510, approximately 6×1019) permutations.
• Economics: Hyperinflation in Zimbabwe estimated in February 2009 by some economists at 10 sextillion percent, or a factor of 1020

## 1021

(1000000000000000000000; 10007; short scale: one sextillion; long scale: one thousand trillion, or one trilliard)

ISO: zetta- (Z)

• Geo — Grains of sand: all the world's beaches put together have been estimated to hold roughly 1021 grains of sand.
• Mathematics — Sudoku: There are 6,670,903,752,021,072,936,960 (≈6.7×1021) 9×9 sudoku grids.
• Astronomy — Stars: 70 sextillion = 7×1022 estimated number of stars within range of telescopes (as of 2003), see mass of the observable universe.
• Mathematics: 146,361,946,186,458,562,560,000 (≈1.5×1023) is the fifth unitary perfect number.
• Chemistry: there are roughly 6.022×1023 molecules in one mole of any substance (Avogadro's number)

## 1024

(1000000000000000000000000; 10008; short scale: one septillion; long scale: one quadrillion)

ISO: yotta- (Y)

• Mathematics: 2,833,419,889,721,787,128,217,599 (≈2.8×1024) is a Woodall prime.

## 1027

(1000000000000000000000000000; 10009; short scale: one octillion; long scale: one thousand quadrillion, or one quadrilliard)

• BioMed — Atoms in the human body: the average human body contains roughly 7×1027 atoms
• Mathematics — Poker: the number of unique combinations of hands and shared cards in a 10-player game of Texas Hold'em is approximately 2.117×1028, see Poker probability (Texas hold 'em).

## 1030

(1000000000000000000000000000000; 100010; short scale: one nonillion; long scale: one quintillion)

• BioMed — Bacterial cells on Earth: The number of bacterial cells on Earth is estimated at around 5,000,000,000,000,000,000,000,000,000,000, or 5 × 1030 
• Mathematics: The partition of 1000 is 24,061,467,864,032,622,473,692,149,727,991.
• Mathematics: 2108 = 324,518,553,658,426,726,783,156,020,576,256 is the last known power of two not containing a digit '9'.

## 1033

(1000000000000000000000000000000000; 100011; short scale: one decillion; long scale: one thousand quintillion, or one quintilliard)

• Mathematics — Alexander's Star: There are 72,431,714,252,715,638,411,621,302,272,000,000 (about 7.24×1034) different positions of Alexander's Star

## 1036

(1000000000000000000000000000000000000; 100012; short scale: one undecillion; long scale: one sextillion)

• Physics: kee2 / Gm2, the ratio of the electromagnetic to the gravitational forces between two protons, is roughly 1036.
• Mathematics: $2^{2^7-1}-1$ = 170,141,183,460,469,231,731,687,303,715,884,105,727 (≈1.7×1038) is a double Mersenne prime.
• Computing: (2128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 (≈3.40282367×1038), the theoretical maximum number of Internet addresses that can be allocated under the IPv6 addressing system, one more than the largest value that can be represented by a single-precision IEEE floating-point value, the total number of different Universally Unique Identifiers (UUIDs) that can be generated.
• Cryptography: 2128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 (≈3.40282367×1038), the total number of different possible keys in the AES 128-bit key space (symmetric cipher).

## 1039

(1000000000000000000000000000000000000000; 100013; short scale: one duodecillion; long scale: one thousand sextillion, or one sextilliard)

• Cosmology: The Eddington–Dirac number is roughly 1040.
• Mathematics: 69,720,375,229,712,477,164,533,808,935,312,303,556,800 (≈7.0×1040) is the least common multiple of every integer from 1 to 100.

## 1042 to 10100

(1000000000000000000000000000000000000000000; 100014; short scale: one tredecillion; long scale: one septillion)

• Mathematics: 141×2141+1 = 393,050,634,124,102,232,869,567,034,555,427,371,542,904,833 (≈3.9×1044) is the second Cullen prime
• Mathematics: There are 7,401,196,841,564,901,869,874,093,974,498,574,336,000,000,000 (≈7.4×1045) possible permutations for the Rubik's Revenge (4x4x4 Rubik's Cube).
• Chess: 4.52×1046 is a proven upper bound for the number of legal chess positions.
• Mathematics: 808,017,424,794,512,875,886,459,904,961,710,757,005,754,368,000,000,000 (≈8×1053) is the order of the Monster group.
• Cryptography: There are 6.27710174×1057 different possible keys in the AES 192 bit key space (symmetric cipher).
• Cosmology: 8×1060 is roughly the number of Planck time intervals since the universe is theorised to have been created in the Big Bang 13.7 ± 0.2 billion years ago.
• Cosmology: 1×1063 is Archimedes’ estimate in The Sand Reckoner of the total number of grains of sand that could fit into the entire cosmos, the diameter of which he estimated to be what we call 2 light years.
• Mathematics — Cards: 52! = 80,658,175,170,943,878,571,660,636,856,403,766,975,289,505,440,883,277,824,000,000,000,000 (≈8×1067) – the number of ways to order the cards in a 52-card deck.
• Mathematics: 1,808,422,353,177,349,564,546,512,035,512,530,001,279,481,259,854,248,860,454,348,989,451,026,887 (≈1.8×1072) – The largest known prime factor found by ECM factorization as of 2010.
• Mathematics: There are 282 870 942 277 741 856 536 180 333 107 150 328 293 127 731 985 672 134 721 536 000 000 000 000 000 (2.8287×1074) possible permutations for the Professor's Cube (5x5x5 Rubik's Cube).
• Cryptography: There are 1.15792089×1077 different possible keys in the AES 256 bit keyspace (symmetric cipher).
• Cosmology: Various sources estimate the total number of fundamental particles in the observable universe to be within in the range of 1080 to 1085. However, these estimates are generally regarded as guesswork.
• Mathematics: 10 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000; 10100, a googol

## 10100 (one googol) to $10^{10^{100}}$ (one googolplex)

• Mathematics: There are 157 152 858 401 024 063 281 013 959 519 483 771 508 510 790 313 968 742 344 694 684 829 502 629 887 168 573 442 107 637 760 000 000 000 000 000 000 000 000 (1.5715 ×10116) distinguishable permutations of the V-Cube 6 (6x6x6 Rubik's Cube).
• Chess: Shannon number, 10120, an estimation of the game-tree complexity of chess.
• Physics: 8×10120, ratio of the mass-energy in the observable universe to the energy of a photon with a wavelength the size of the observable universe.
• History — Religion: Asaṃkhyeya is a Buddhist name for the number 10140. It is listed in the Avatamsaka Sutra and metaphorically means "innumerable" in the Sanskrit language of ancient India.
• Xiangqi: 10150, an estimation of the game-tree complexity of xiangqi.
• Mathematics: There are 19 500 551 183 731 307 835 329 126 754 019 748 794 904 992 692 043 434 567 152 132 912 323 232 706 135 469 180 065 278 712 755 853 360 682 328 551 719 137 311 299 993 600 000 000 000 000 000 000 000 000 000 000 000 (1.9501 ×10160) distinguishable permutations of the V-Cube 7 (7x7x7 Rubik's Cube).
• Board games: 3.457×10181, number of ways to arrange the tiles in English Scrabble on a standard 15-by-15 Scrabble board.
• Physics: 4×10185, approximate number of Planck volumes in the observable universe.
• Computing: 1.797 693 134 862 3157×10308 is approximately equal to the largest value that can be represented in the IEEE double precision floating-point format.
• Go: 10365, an estimation of the game-tree complexity in the game of Go.[citation needed]
• Mathematics: 26384405 + 44052638 is a 15,071-digit Leyland prime; the largest which has been proven as of 2010.
• Mathematics: 183,027 × 2265,440−1 is a 79,911-digit Sophie Germain prime; the largest known as of March 2010.
• Mathematics: 65,516,468,355 · 2333,333 ± 1 are 100,355-digit twin primes; the largest known as of 2010.
• Mathematics: 10200000 + 47960506974×1099995 + 1 is a 200,001-digit palindromic prime, the largest known as of December 2010.
• Mathematics: approximately 7.76 · 10206,544 cattle in the smallest herd which satisfies the conditions of the Archimedes' cattle problem.
• Mathematics: 843,301# – 1 is a 365,851-digit primorial prime; the largest known as of 2010.
• Mathematics: 110,059! + 1 is a 507,082-digit factorial prime; the largest known as of June 2011.
• Mathematics: 145,310262,144 + 1 is a 1,353,265-digit Generalized Fermat prime, the largest known as of 2011.
• Mathematics — Literature: Jorge Luis Borges' Library of Babel contains at least $25^{1,312,000} \approx 1.956 \times 10^{1,834,097}$ books (this is a lower bound).
• Mathematics: 19,249 × 213,018,586 + 1 is a 3,918,990-digit Proth prime, the largest known Proth prime and non-Mersenne prime as of 2010.
• Mathematics: 243,112,609 − 1 is a 12,978,189-digit Mersenne prime; the largest known prime of any kind as of 2010.
• Mathematics: 243,112,608 × (243,112,609 − 1) is a 25,956,377-digit perfect number, the largest known as of 2010.
• Mathematics — History: 1080,000,000,000,000,000, largest named number in Archimedes' Sand Reckoner.
• Mathematics: 10googol ( $10^{10^{100}}$), a googolplex.

## Larger than $10^{10^{100}}$ (one googolplex)

• Cosmology: In chaotic inflation theory, proposed by physicist Andrei Linde, our universe is one of many other universes with different physical constants that originated as part of our local section of the multiverse, owing to a vacuum that had not decayed to its ground state. According to Linde and Vanchurin, the total number of these universes is about $10^{10^{10,000,000}}$.
• Mathematics—Literature: The number of different ways in which the books in Luis Borges' Library of Babel can be arranged is $10^{10^{33,013,740}}$.
• Mathematics: $10^{\,\!10^{10^{34}}}$, order of magnitude of an upper bound that occurred in a proof of Skewes (later estimated to actually be near 1.397 × 10316).
• Mathematics: $10^{\,\!10^{10^{1000}}}$, order of magnitude of another upper bound in a proof of Skewes.
• Mathematics: Moser's number "2 in a mega-gon" is approximately equal to 10↑↑↑...↑↑↑10, where there are 10↑↑257 arrows.
• Mathematics: Graham's number, the last ten digits of which are ...24641 95387. Arises as an upper bound solution to a problem in Ramsey theory. Representation in powers of 10 would be impractical (the number of digits in the exponent far exceeds the number of particles in the observable universe).
• Mathematics: TREE(3): appears in relation to a theorem on trees in graph theory. Representation of the number is difficult, but one weak lower bound is AA(187196)(1), where A(n) is a version of the Ackermann function.

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