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1089 (number)
1089 is the integer after 1088 and before 1090. It is a square number (33 squared), a nonagonal number, a 32-gonal number, a 364-gonal number, and a centered octagonal number. 1089 is the first reverse-divisible number. The next is 2178 , and they are the only four-digit numbers that divide their reverse. In magic 1089 is widely used in magic tricks because it can be "produced" from any two three-digit numbers. This allows it to be used as the basis for a Magician's Choice. For instance, one variation of the book test starts by having the spectator choose any two suitable numbers and then apply some basic maths to produce a single four-digit number. That number is always 1089. The spectator is then asked to turn to page 108 of a book and read the 9th word, which the magician has memorized. To the audience it looks like the number is random, but through manipulation, the result is always the same. In base 10, the following steps always yield 1089: # Take any three-digit number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the language of mathematics, the set of integers is often denoted by the boldface or blackboard bold \mathbb. The set of natural numbers \mathbb is a subset of \mathbb, which in turn is a subset of the set of all rational numbers \mathbb, itself a subset of the real numbers \mathbb. Like the natural numbers, \mathbb is countably infinite. An integer may be regarded as a real number that can be written without a fractional component. For example, 21, 4, 0, and −2048 are integers, while 9.75, , and are not. The integers form the smallest group and the smallest ring containing the natural numbers. In algebraic number theory, the integers are sometimes qualified as rational integers to distinguish them from the more general algebraic integers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square Number
In mathematics, a square number or perfect square is an integer that is the square (algebra), square of an integer; in other words, it is the multiplication, product of some integer with itself. For example, 9 is a square number, since it equals and can be written as . The usual notation for the square of a number is not the product , but the equivalent exponentiation , usually pronounced as " squared". The name ''square'' number comes from the name of the shape. The unit of area is defined as the area of a unit square (). Hence, a square with side length has area . If a square number is represented by ''n'' points, the points can be arranged in rows as a square each side of which has the same number of points as the square root of ''n''; thus, square numbers are a type of figurate numbers (other examples being Cube (algebra), cube numbers and triangular numbers). Square numbers are non-negative. A non-negative integer is a square number when its square root is again an intege ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonagonal Number
A nonagonal number (or an enneagonal number) is a figurate number that extends the concept of triangular number, triangular and square numbers to the nonagon (a nine-sided polygon). However, unlike the triangular and square numbers, the patterns involved in the construction of nonagonal numbers are not rotationally symmetrical. Specifically, the ''n''th nonagonal number counts the number of dots in a pattern of ''n'' nested nonagons, all sharing a common corner, where the ''i''th nonagon in the pattern has sides made of ''i'' dots spaced one unit apart from each other. The nonagonal number for ''n'' is given by the formula: :\frac . Nonagonal numbers The first few nonagonal numbers are: :0 (number), 0, 1 (number), 1, 9 (number), 9, 24 (number), 24, 46 (number), 46, 75 (number), 75, 111 (number), 111, 154 (number), 154, 204 (number), 204, 261, 325, 396, 474, 559, 651, 750, 856, 969, 1089 (number), 1089, 1216, 1350, 1491, 1639, 1794, 1956, 2125, 2301, 2484, 2674, 2871, 3075, 3286, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centered Octagonal Number
A centered octagonal number is a centered figurate number that represents an octagon with a dot in the center and all other dots surrounding the center dot in successive octagonal layers.. The centered octagonal numbers are the same as the odd square numbers. Thus, the ''n''th odd square number and ''t''th centered octagonal number is given by the formula :O_n=(2n-1)^2 = 4n^2-4n+1 , (2t+1)^2=4t^2+4t+1. The first few centered octagonal numbers are : 1, 9, 25, 49, 81, 121, 169, 225, 289, 361, 441, 529, 625, 729, 841, 961, 1089, 1225 Calculating Ramanujan's tau function on a centered octagonal number yields an odd number, whereas for any other number the function yields an even number. O_n is the number of 2x2 matrices with elements from 0 to n that their determinant is twice their permanent. See also * Octagonal number An octagonal number is a figurate number that represents an octagon. The octagonal number for ''n'' is given by the formula 3''n''2 - 2''n'', with ''n' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse-divisible Number
In number theory, reversing the digits of a number sometimes produces another number that is divisible by . This happens trivially when is a palindromic number; the nontrivial reverse divisors are :1089, 2178, 10989, 21978, 109989, 219978, 1099989, 2199978, ... . For instance, 1089 × 9 = 9801, the reversal of 1089, and 2178 × 4 = 8712, the reversal of 2178... The multiples produced by reversing these numbers, such as 9801 or 8712, are sometimes called palintiples. Properties Every nontrivial reverse divisor must be either 1/4 or 1/9 of its reversal. The number of -digit nontrivial reverse divisors is 2F(\lfloor(d-2)/2\rfloor) where F(i) denotes the th Fibonacci number. For instance, there are two four-digit reverse divisors, matching the formula 2F(\lfloor(d-2)/2\rfloor)=2F(1)=2. History The reverse divisor properties of the first two of these numbers, 1089 and 2178, were mentioned by W. W. Rouse Ball in his ''Mathematical Recreations''. In ''A Mathematician's Apology'', G. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2178 (number)
2000 (two thousand) is a natural number following 1999 and preceding 2001. It is: :*the highest number expressible using only two unmodified characters in Roman numerals (MM) :*an Achilles number :*smallest four digit eban number Selected numbers in the range 2001–2999 2001 to 2099 * 2001 – sphenic number * 2002 – palindromic number * 2003 – Sophie Germain prime and the smallest prime number in the 2000s * 2004 – Area of the 24tcrystagon* 2005 – A vertically symmetric number * 2006 – number of subsets of with relatively prime elements * 2007 – 22007 + 20072 is prime * 2008 – number of 4 X 4 matrices with nonnegative integer entries and row and column sums equal to 3 * 2009 = 74 − 73 − 72 * 2010 – number of compositions of 12 into relatively prime parts * 2011 – Sexy prime with 2017, sum of eleven consecutive primes: 2011 = 157 + 163 + 167 + 173 + 179 + 181 + 191 + 193 + 197 + 199 + 211 * 2012 – The number 8 × 102012 − 1 is a prime number * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magic Trick
Magic, which encompasses the subgenres of illusion, stage magic, and close up magic, among others, is a performing art in which audiences are entertained by tricks, effects, or illusions of seemingly impossible feats, using natural means. It is to be distinguished from paranormal magic which are effects claimed to be created through supernatural means. It is one of the oldest performing arts in the world. Modern entertainment magic, as pioneered by 19th-century magician Jean-Eugène Robert-Houdin, has become a popular theatrical art form. In the late 19th and early 20th centuries, magicians such as Maskelyne and Devant, Howard Thurston, Harry Kellar, and Harry Houdini achieved widespread commercial success during what has become known as "the Golden Age of Magic." During this period, performance magic became a staple of Broadway theatre, vaudeville, and music halls. Magic retained its popularity in the television age, with magicians such as Paul Daniels, David Copperfield, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magician's Choice
In stage magic, a force is a method of controlling a choice made by a spectator during a trick. Some forces are performed physically using sleight of hand, such as a trick where a spectator appears to select a random card from a deck but is instead handed a known card by the magician. Other forces use equivocation (or "the magician's choice") to create the illusion of a free decision in a situation where all choices lead to the same outcome. Equivocation Equivocation (or the magician's choice) is a verbal technique by which a magician gives an audience member an apparently free choice but frames the next stage of the trick in such a way that each choice has the same end result. An example of equivocation can be as follows: A performer deals two cards on a table and asks a spectator to select one. If the spectator chooses the card on the left, the performer will hand the card to the spectator. If they pick the card on the right, the performer will take that card as his own and ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Book Test
The book test is a classic mentalism demonstration used by Mentalism, mentalists to demonstrate telepathy-like effects. The name refers to its early use as a test of mental powers. Effect An audience member (the "spectator") is called onstage to assist the mentalist. The spectator is shown one or more books, and asked to read a random passage from one of them. The passage may be revealed to the audience, or recorded in some other way for later comparison. The mentalist then typically presents a routine to establish an atmosphere or back story, and proceeds to read the spectator's mind to reveal elements relating to the passage read by the spectator. History Books have been used as props as long ago as the 1450s. In one particularly common trick, the "magic coloring book, blow book", spectators would blow on the pages of a book which would then reveal images, colors, or text. However, these were not similar to modern book tests, as the "magic" was simply the change in appearance.W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radix
In a positional numeral system, the radix or base is the number of unique digits, including the digit zero, used to represent numbers. For example, for the decimal/denary system (the most common system in use today) the radix (base number) is ten, because it uses the ten digits from 0 through 9. In any standard positional numeral system, a number is conventionally written as with ''x'' as the string of digits and ''y'' as its base, although for base ten the subscript is usually assumed (and omitted, together with the pair of parentheses), as it is the most common way to express value. For example, (the decimal system is implied in the latter) and represents the number one hundred, while (100)2 (in the binary system with base 2) represents the number four. Etymology ''Radix'' is a Latin word for "root". ''Root'' can be considered a synonym for ''base,'' in the arithmetical sense. In numeral systems In the system with radix 13, for example, a string of digits such as 398 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
