30-631: Number Four may refer to: 4 (number) , a number, numeral, and glyph A hamlet in the town of Watson, New York #4, the pseudonym of American musician Jim Root , when performing with Slipknot A character from the Earthworm Jim video games and animated series Numbuh Four , a character from Codename: Kids Next Door A predominantly defensive position in polo Jean Béliveau (1931–2014), Canadiens hockey player, frequently known by his sweater number, number 4 A character also known as Simon in
60-580: A rectangle or oblong , kite , rhombus , and square . Four is the highest degree general polynomial equation for which there is a solution in radicals . The four-color theorem states that a planar graph (or, equivalently, a flat map of two-dimensional regions such as countries) can be colored using four colors, so that adjacent vertices (or regions) are always different colors. Three colors are not, in general, sufficient to guarantee this. The largest planar complete graph has four vertices. A solid figure with four faces as well as four vertices
90-455: A cross that looks like the modern plus sign. The Shunga would add a horizontal line on top of the digit, and the Kshatrapa and Pallava evolved the digit to a point where the speed of writing was a secondary concern. The Arabs ' 4 still had the early concept of the cross, but for the sake of efficiency, was made in one stroke by connecting the "western" end to the "northern" end; the "eastern" end
120-597: A limited number of segments in seven-segment displays, a couple of the hexadecimal digits are required to be displayed as lowercase letters, otherwise the uppercase letter "B" would be the same as the digit "8", and the uppercase letter "D" would be the same as the digit "0". The digit "6" must also be displayed with the topmost segment as [REDACTED] to avoid ambiguity with the letter "b". Early decoder IC's often produced random patterns or duplicates of digits for 10-15, as they were designed to use as few gates as possible and only required to produce 0-9. Many letters of
150-441: A method of telegraphically transmitting letters and numbers and having them printed on tape in a segmented format. In 1908, F. W. Wood invented an 8-segment display, which displayed the number 4 using a diagonal bar ( U.S. patent 974,943 ). In 1910, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel. They were also used to show the dialed telephone number to operators during
180-447: A rectangle, with two vertical segments on each side and one horizontal segment each at the top, middle, and bottom. Often the rectangle is oblique (slanted), which may aid readability. In most applications, the segments are of nearly uniform shape and size (usually elongated hexagons , though trapezoids and rectangles can also be used); though in the case of adding machines , the vertical segments are longer and more oddly shaped at
210-734: A restricted range of letters that look like (upside-down) digits, seven-segment displays are commonly used by school children to form words and phrases using a technique known as " calculator spelling ". Seven-segment displays may use a liquid-crystal display (LCD), a light-emitting diode (LED) for each segment, an electrochromic display , or other light-generating or -controlling techniques such as cold cathode gas discharge (neon) ( Panaplex ), vacuum fluorescent (VFD), incandescent filaments (Numitron), and others. For gasoline price totems and other large signs, electromechanical seven-segment displays made up of electromagnetically flipped light-reflecting segments are still commonly used. A precursor to
240-457: A seven-segment digit template , to compose figures such as product prices or telephone numbers. For many applications, dot-matrix liquid-crystal displays (LCDs) have largely superseded LED displays in general, though even in LCDs, seven-segment displays are common. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by photolithography . In contrast,
270-446: A seven-segment display, including the decimal point. The most popular bit encodings are gfedcba and abcdefg . In the gfedcba representation, a byte value of 0x06 would turn on segments "c" and "b", which would display a "1". The numerical digits 0 to 9 are the most common characters displayed on seven-segment displays. The most common patterns used for each of these are: Alternative patterns: The numeral 1 may be represented with
300-640: A simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a "common cathode" or "common anode" device. Hence a 7 segment plus decimal point package will only require nine pins, though commercial products typically contain more pins, and/or spaces where pins would go, in order to match standard IC sockets. Integrated displays also exist, with single or multiple digits. Some of these integrated displays incorporate their own internal decoder , though most do not: each individual LED
330-1629: Is a tetrahedron , which is the smallest possible number of faces and vertices a polyhedron can have. The regular tetrahedron, also called a 3- simplex , is the simplest Platonic solid . It has four regular triangles as faces that are themselves at dual positions with the vertices of another tetrahedron. The smallest non- cyclic group has four elements; it is the Klein four-group . A n alternating groups are not simple for values n {\displaystyle n} ≤ 4 {\displaystyle 4} . There are four Hopf fibrations of hyperspheres : S 0 ↪ S 1 → S 1 , S 1 ↪ S 3 → S 2 , S 3 ↪ S 7 → S 4 , S 7 ↪ S 15 → S 8 . {\displaystyle {\begin{aligned}S^{0}&\hookrightarrow S^{1}\to S^{1},\\S^{1}&\hookrightarrow S^{3}\to S^{2},\\S^{3}&\hookrightarrow S^{7}\to S^{4},\\S^{7}&\hookrightarrow S^{15}\to S^{8}.\\\end{aligned}}} They are defined as locally trivial fibrations that map f : S 2 n − 1 → S n {\displaystyle f:S^{2n-1}\rightarrow S^{n}} for values of n = 2 , 4 , 8 {\displaystyle n=2,4,8} (aside from
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#1732858909574360-454: Is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays . Seven-segment displays are widely used in digital clocks , electronic meters, basic calculators, and other electronic devices that display numerical information. Seven-segment representation of figures can be found in patents as early as 1903 (in U.S. patent 1,126,641 ), when Carl Kinsley invented
390-399: Is a number, numeral and digit. It is the natural number following 3 and preceding 5. 4 is the smallest square number > 1, the smallest semiprime and composite number , and the 3rd highly composite number . The number 4 is considered unlucky in many East Asian cultures. Brahmic numerals represented 1, 2, and 3 with as many lines. 4 was simplified by joining its four lines into
420-468: Is brought out to a connecting pin as described. Multiple-digit LED displays as used in pocket calculators and similar devices used multiplexed displays to reduce the number of I/O pins required to control the display. For example, all the anodes of the A segments of each digit position would be connected together and to a driver circuit pin, while the cathodes of all segments for each digit would be connected. To operate any particular segment of any digit,
450-681: Is seen with an open top: [REDACTED] . Television stations that operate on channel 4 have occasionally made use of another variation of the "open 4", with the open portion being on the side, rather than the top. This version resembles the Canadian Aboriginal syllabics letter ᔦ. The magnetic ink character recognition "CMC-7" font also uses this variety of "4". There are four elementary arithmetic operations in mathematics: addition ( + ), subtraction ( − ), multiplication ( × ), and division ( ÷ ). Lagrange's four-square theorem states that every positive integer can be written as
480-437: The latin alphabet can be reasonably implemented on a seven-segment display. Though not every letter is available, it is possible to create many useful words. By careful choice of words, one can sometimes work around unavailable letters. Uppercase letters "I", "O", "S", "Z" conflict with the common seven-segment representation of digits "1", "0", 5", "2", and the lowercase letter "g" with digit "9". Upper case I could be put on
510-442: The 1970s. Many early (c. 1970s) LED seven-segment displays had each digit built on a single die . This made the digits very small. Some included magnifying lenses in the design to try to make the digits more legible. Other designs used 1 or 2 dies for every segment of the display. The seven-segment pattern is sometimes used in posters or tags, where the user either applies color to pre-printed segments, or applies color through
540-459: The 7-segment display in the 1950s through the 1970s was the cold-cathode, neon-lamp-like nixie tube . Starting in 1970, RCA sold a display device known as the Numitron that used incandescent filaments arranged into a seven-segment display. In USSR, the first electronic calculator "Vega", which was produced from 1964, contains 20 decimal digits with seven-segment electroluminescent display . In
570-464: The controlling integrated circuit would turn on the cathode driver for the selected digit, and the anode drivers for the desired segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit display with seven segments and a decimal point would require only 8 cathode drivers and 8 anode drivers, instead of sixty-four drivers and IC pins. Often in pocket calculators
600-502: The digit drive lines would be used to scan the keyboard as well, providing further savings; however, pressing multiple keys at once would produce odd results on the multiplexed display. Although to a naked eye all digits of an LED display appear lit, only one digit is lit at any given time in a multiplexed display. The digit changes at a high enough rate that the human eye cannot see the flashing (on earlier devices it could be visible to peripheral vision). The seven segments are arranged as
630-459: The ends, to try to make them more easily readable. The seven elements of the display can be lit in different combinations to represent each of the Arabic numerals . The individual segments are referred to by the letters "a" to "g", and an optional decimal point (an "eighth segment", referred to as DP) is sometimes used for the display of non-integer numbers. A single byte can encode the full state of
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#1732858909574660-439: The left (as lower-case L is shown here) but this is not often done. Lowercase 'b' and 'q' are identical to the alternate numerical digits '6' and '9'. The following are some real world english word examples seen on actual electronic equipment: There are also fourteen- and sixteen-segment displays (for full alphanumerics ); however, these have mostly been replaced by dot matrix displays . 22-segment displays capable of displaying
690-677: The left segments, the numerals 6 and 9 may be represented without a "tail", and the numeral 7 represented with a 'tail': In Unicode 13.0, 10 codepoints had been given for segmented digits 0–9 in the Symbols for Legacy Computing block, to replicate early computer fonts that included seven-segment versions of the digits. The official reference shows the less-common four-segment "7". The binary-coded decimal (BCD) 0 to 9 digit values require four binary bits to hold their values. Since four bits (2 ) can hold 16 values, this means hexadecimal (hex) digits can be represented by four bits too. Since there are
720-454: The reimagined Battlestar Galactica A character in the 2011 film I Am Number Four , based on the 2010 book of the same name "Number Four" (single) , a 2013 single by My Chemical Romance Number 4 (album) , also styled as #4 , a 2005 album by Ling Tosite Sigure See also [ edit ] Four (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
750-639: The shapes of LED segments tend to be simple rectangles , because they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of seven-segment displays. However, the easy recognition of seven-segment displays, and the comparatively high visual contrast obtained by such displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD screens very common on basic calculators . The seven-segment display has inspired type designers to produce typefaces reminiscent of that display (but more legible), such as New Alphabet , "DB LCD Temp", "ION B", etc. Using
780-421: The sum of at most four squares . Four is one of four all-Harshad numbers . Each natural number divisible by 4 is a difference of squares of two natural numbers, i.e. 4 x = y 2 − z 2 {\displaystyle 4x=y^{2}-z^{2}} . A four-sided plane figure is a quadrilateral or quadrangle, sometimes also called a tetragon . It can be further classified as
810-460: The title Number Four . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Number_Four&oldid=1233045738 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages 4 (number) 4 (four)
840-766: The transition from manual to automatic telephone dialing. They did not achieve widespread use until the advent of LEDs in the 1970s. Some early seven-segment displays used incandescent filaments in an evacuated bulb; they are also known as numitrons. A variation (minitrons) made use of an evacuated potted box. Minitrons are filament segment displays that are housed in DIP ( dual in-line package ) packages like modern LED segment displays. They may have up to 16 segments . There were also segment displays that used small incandescent light bulbs instead of LEDs or incandescent filaments. These worked similarly to modern LED segment displays. Vacuum fluorescent display versions were also used in
870-508: The trivial fibration mapping between two points and a circle ). In Knuth's up-arrow notation , 2 + 2 = 2 × 2 = 2 2 = 2 ↑ ↑ 2 = 2 ↑ ↑ ↑ 2 = . . . = 4 {\displaystyle 2+2=2\times 2=2^{2}=2\uparrow \uparrow 2=2\uparrow \uparrow \uparrow 2=\;...\;=4} , and so forth, for any number of up arrows. Seven-segment display A seven-segment display
900-523: Was finished off with a curve. The Europeans dropped the finishing curve and gradually made the digit less cursive, ending up with a digit very close to the original Brahmin cross. While the shape of the character for the digit 4 has an ascender in most modern typefaces , in typefaces with text figures the glyph usually has a descender , as, for example, in [REDACTED] . On the seven-segment displays of pocket calculators and digital watches, as well as certain optical character recognition fonts, 4
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