|
20 (number)
20 (twenty; Roman numeral XX) is the natural number following 19 and preceding 21. A group of twenty units may also be referred to as a score. In mathematics *20 is a pronic number. *20 is a tetrahedral number as 1, 4, 10, 20. *20 is the basis for vigesimal number systems. *20 is the third composite number to be the product of a squared prime and a prime, and also the second member of the (''2''2)''q'' family in this form. *20 is the smallest primitive abundant number. *An icosahedron has 20 faces. A dodecahedron has 20 vertices. *20 can be written as the sum of three Fibonacci numbers uniquely, i.e. 20 = 13 + 5 + 2. *20 is the number of moves (quarter or half turns) required to optimally solve a Rubik's Cube in the worst case. (e.g. the newspaper headline "Scores of Typhoon Survivors Flown to Manila")."CBS News"''Scores of Typhoon Survivors Flown to Manila'' (November 2013) In sports * Twenty20 is a form of limited overs cricket where each team plays only 20 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vigesimal
vigesimal () or base-20 (base-score) numeral system is based on twenty (in the same way in which the decimal numeral system is based on ten). '' Vigesimal'' is derived from the Latin adjective '' vicesimus'', meaning 'twentieth'. Places In a vigesimal place system, twenty individual numerals (or digit symbols) are used, ten more than in the usual decimal system. One modern method of finding the extra needed symbols is to write ten as the letter (the 20 means base ), to write nineteen as , and the numbers between with the corresponding letters of the alphabet. This is similar to the common computer-science practice of writing hexadecimal numerals over 9 with the letters "A–F". Another less common method skips over the letter "I", in order to avoid confusion between I20 as eighteen and one, so that the number eighteen is written as J20, and nineteen is written as K20. The number twenty is written as . According to this notation: : is equivalent to forty in decimal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magic Number (physics)
In nuclear physics, a magic number is a number of nucleons (either protons or neutrons, separately) such that they are arranged into complete Nuclear shell model, shells within the atomic nucleus. As a result, atomic nuclei with a 'magic' number of protons or neutrons are much more stable than other nuclei. The seven most widely recognized magic numbers as of 2019 are 2, 8, 20, 28, 50, 82, and 126 . For protons, this corresponds to the elements helium, oxygen, calcium, nickel, tin, lead and the hypothetical unbihexium, although 126 is so far only known to be a magic number for neutrons. Atomic nuclei consisting of such a magic number of nucleons have a higher average binding energy per nucleon than one would expect based upon predictions such as the semi-empirical mass formula and are hence more stable against nuclear decay. The unusual stability of isotopes having magic numbers means that transuranium elements could theoretically be created with extremely large nuclei and yet n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Over (cricket)
In cricket, an over consists of six legal deliveries bowled from one end of a cricket pitch to the player batting at the other end, almost always by a single bowler. A maiden over is an over in which no runs are scored that count against the bowler (so leg byes and byes may be scored as they are not counted against the bowler). A wicket maiden is a maiden over in which a wicket is also taken. Similarly, double and triple wicket maidens are when two and three wickets are taken in a maiden over. After six deliveries the umpire calls 'over'; the fielding team switches ends, and a different bowler is selected to bowl from the opposite end. The captain of the fielding team decides which bowler will bowl any given over, and no bowler may bowl two overs in succession. Overview Although this has not always been so, with overs of four and eight balls used in the past, currently an over must consist of six legal deliveries. If the bowler bowls a wide or a no-ball, that illegal deliv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limited Overs Cricket
Limited overs cricket, also known as one-day cricket or white ball cricket, is a version of the sport of cricket in which a match is generally completed in one day. There are a number of formats, including List A cricket (8-hour games), Twenty20 cricket (3-hour games), and 100-ball cricket (2.5 hours). The name reflects the rule that in the match each team bowls a set maximum number of overs (sets of 6 legal balls), usually between 20 and 50, although shorter and longer forms of limited overs cricket have been played. The concept contrasts with Test and first-class matches, which can take up to five days to complete. One-day cricket is popular with spectators as it can encourage aggressive, risky, entertaining batting, often results in cliffhanger endings, and ensures that a spectator can watch an entire match without committing to five days of continuous attendance. Structure Each team bats only once, and each innings is limited to a set number of overs, usually fift ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twenty20
Twenty20 (T20) is a shortened game format of cricket. At the professional level, it was introduced by the England and Wales Cricket Board (ECB) in 2003 for the inter-county competition. In a Twenty20 game, the two teams have a single innings each, which is restricted to a maximum of 20 overs. Together with first-class and List A cricket, Twenty20 is one of the three current forms of cricket recognised by the International Cricket Council (ICC) as being at the highest international or domestic level. A typical Twenty20 game is completed in about two and a half hours, with each innings lasting around 70 minutes and an official 10-minute break between the innings. This is much shorter than previous forms of the game, and is closer to the timespan of other popular team sports. It was introduced to create a fast-paced game that would be attractive to spectators at the ground and viewers on television. The game has succeeded in spreading around the cricket world. On most in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dartboard Unlabeled
Darts or dart-throwing is a competitive sport in which two or more players bare-handedly throw small sharp-pointed missiles known as darts at a round target known as a dartboard. Points can be scored by hitting specific marked areas of the board, though unlike in sports such as archery, these areas are distributed all across the board and do not follow a principle of points increasing towards the centre of the board. Though a number of similar games using various boards and rules exist, the term "darts" usually now refers to a standardised game involving a specific board design and set of rules. Darts is both a professional shooting sport and a traditional pub game. Darts is commonly played in the United Kingdom and the Republic of Ireland, and recreationally enjoyed around the world. History Dartboard The original target in the game is likely to have been a section of a tree trunk, its circular shape and concentric rings giving rise to the standard dartboard pattern in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Retired Numbers
This pages lists retired numbers which sports teams or bodies have withdrawn as a tribute, usually to a former player. The list is ordered by number. 00 National Basketball Association (NBA) *The Boston Celtics, for Hall of Famer Robert Parish. *The San Antonio Spurs, for Johnny Moore. 1 Major League Baseball (MLB) * The Boston Red Sox, for Hall of Famer Bobby Doerr. * The Cincinnati Reds, for manager Fred Hutchinson. * The Los Angeles Dodgers, for Hall of Famer Pee Wee Reese. * The Milwaukee Brewers, for Hall of Famer and former owner, Bud Selig. * The New York Yankees, for Billy Martin, who both played for and managed the team. * The Philadelphia Phillies, for Hall of Famer Richie Ashburn. * The Pittsburgh Pirates, for manager Billy Meyer. * The St. Louis Cardinals, for Hall of Famer Ozzie Smith. NBA * The Boston Celtics, for founding owner Walter Brown, a member of the Hall of Fame as a contributor. * The Milwaukee Bucks, for Hall of Fame player Oscar Robertson. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indefinite And Fictitious Numbers
Many languages have words expressing indefinite and fictitious numbers—inexact terms of indefinite size, used for comic effect, for exaggeration, as placeholder names, or when precision is unnecessary or undesirable. One technical term for such words is "non-numerical vague quantifier". Such words designed to indicate large quantities can be called "indefinite hyperbolic numerals". Specific values used as indefinite * In English, some words that have a precise numerical definition are often used indefinitely: couple, 2; dozen, 12; score, 20; myriad, 10,000. Unlike cardinal numbers these can be pluralized, in which case they require ''of'' before the noun (''millions of dollars'', but ''five million dollars'') and require the indefinite article "a" in the singular (''a million letters'' (indefinite) but ''one million letters'' (definite)). * In various Middle Eastern traditions, the number 40 is used to express a large but unspecific number,"Biblical Criticism", ''The Classica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardinal Number
In mathematics, cardinal numbers, or cardinals for short, are a generalization of the natural numbers used to measure the cardinality (size) of sets. The cardinality of a finite set is a natural number: the number of elements in the set. The '' transfinite'' cardinal numbers, often denoted using the Hebrew symbol \aleph ( aleph) followed by a subscript, describe the sizes of infinite sets. Cardinality is defined in terms of bijective functions. Two sets have the same cardinality if, and only if, there is a one-to-one correspondence (bijection) between the elements of the two sets. In the case of finite sets, this agrees with the intuitive notion of size. In the case of infinite sets, the behavior is more complex. A fundamental theorem due to Georg Cantor shows that it is possible for infinite sets to have different cardinalities, and in particular the cardinality of the set of real numbers is greater than the cardinality of the set of natural numbers. It is also possible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperial Units
The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed through a series of Weights and Measures Acts and amendments. The imperial system developed from earlier English units as did the related but differing system of customary units of the United States. The imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825. The system came into official use across the British Empire in 1826. By the late 20th century, most nations of the former empire had officially adopted the metric system as their main system of measurement, but imperial units are still used alongside metric units in the United Kingdom and in some other parts of the former empire, notably Canada. The modern UK legislation defining the imperial system of units is given in the Weights and Measures ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Acuity
Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, i.e. (1) the sharpness of the retinal image within the eye, (2) the health and functioning of the retina, and (3) the sensitivity of the interpretative faculty of the brain. The most commonly referred visual acuity is the far acuity (e.g. 6/6 or 20/20 acuity), which describes the examinee's ability to recognize small details at a far distance, and is relevant to people with myopia; however, for people with hyperopia, the near acuity is used instead to describe the examinee's ability to recognize small details at a near distance. A common cause of low visual acuity is refractive error (ametropia), errors in how the light is refracted in the eyeball, and errors in how the retinal image is interpreted by the brain. The latter is the primary cause for low vision in people with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Over (cricket)")
