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Square Root Day
Square Root Day is an unofficial holiday celebrated on days when both the day of the month and the month are the square root of the last two digits of the year. For example, the last Square Root Day was April 4, 2016 (4/4/16), and the next Square Root Day will be May 5, 2025 (5/5/25). The final Square Root Day of the century will occur on September 9, 2081. Square Root Days fall upon the same nine dates each century. Ron Gordon, a Redwood City, California high school teacher, created the first Square Root Day for September 9, 1981 (9/9/81). Gordon remains the holiday's publicist, sending news releases to world media outlets. Gordon's daughter set up a Facebook group where people can share how they were celebrating the day. One suggested way of celebrating the holiday is by eating radishes or other root vegetables cut into shapes with square cross sections (thus creating a "square root"). Full list Square Root Day occurs on the following dates each century: *1/1/01 *2/2/04 *3/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holiday
A holiday is a day set aside by custom or by law on which normal activities, especially business or work including school, are suspended or reduced. Generally, holidays are intended to allow individuals to celebrate or commemorate an event or tradition of cultural or religious significance. Holidays may be designated by governments, religious institutions, or other groups or organizations. The degree to which normal activities are reduced by a holiday may depend on local laws, customs, the type of job held or personal choices. The concept of holidays often originated in connection with religious observances or associated with traditions. The intention of a holiday was typically to allow individuals to tend to religious duties associated with important dates on the calendar. In most modern societies, however, holidays serve as much of a recreational functions as any other weekend days or activities. In many societies, there are important distinctions between holidays designated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross Section (geometry)
In geometry and science, a cross section is the non-empty intersection of a solid body in three-dimensional space with a plane, or the analog in higher-dimensional spaces. Cutting an object into slices creates many parallel cross-sections. The boundary of a cross-section in three-dimensional space that is parallel to two of the axes, that is, parallel to the plane determined by these axes, is sometimes referred to as a contour line; for example, if a plane cuts through mountains of a raised-relief map parallel to the ground, the result is a contour line in two-dimensional space showing points on the surface of the mountains of equal elevation. In technical drawing a cross-section, being a projection of an object onto a plane that intersects it, is a common tool used to depict the internal arrangement of a 3-dimensional object in two dimensions. It is traditionally crosshatched with the style of crosshatching often indicating the types of materials being used. With computed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unofficial Observances
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Sequential Day
A sequential time is one in which the numbers form a normal sequence, such as 1:02:03 4/5/06 (two minutes and three seconds past 1 am on 4 May 2006 (or April 5, 2006 in the United States) or the same time and date in the "06" year of any other century). Short sequential times such as 1:23:45 or 12:34:56 appear every day. Larger sequential times rarely appear, such as 12:34:56 7/8/90, or 01:23:45 on 6/7/89. These times can be dependent on the date format being used; the ''month/day'' format will produce different results from the ''day/month'' format. This term, however, is not limited to simple counting. Other sequences, such as the decimal numbers of the mathematical constants ( 3/14/1592), (2/7/1828), and the square root of two (1/4/1421) are also noted. Number sequences such as the Fibonacci sequence (1/1/2358) can also be found in time stamps. These dates are particularly popular with couples getting married who are seeking unique wedding and anniversary dates. Dates with re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi Day
Pi Day is an annual celebration of the mathematical constant (pi). Pi Day is observed on March 14 (3/14 in the ''month/day'' format) since 3, 1, and 4 are the first three significant figures of . It was founded in 1988 by Larry Shaw, an employee of the San Francisco, California science museum, the Exploratorium. Celebrations often involve eating pie or holding pi recitation competitions. In 2009, the United States House of Representatives supported the designation of Pi Day.United States. Cong. House. Supporting the designation of Pi Day, and for other purposes. 111th CongLibrary of Congress UNESCO's 40th General Conference designated Pi Day as the International Day of Mathematics in November 2019. Alternative dates for the holiday include July 2222 July in the ''day/month'' format (22/7, an approximation of ) and June 28 (6.28, an approximation of 2 or tau). History In 1988, the earliest known official or large-scale celebration of Pi Day was organized by Larry Shaw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mole Day
Mole Day is an unofficial holiday celebrated among chemists, chemistry students and chemistry enthusiasts on October 23, between 6:02 a.m. and 6:02 p.m., making the date 6:02 10/23 in the American style of writing dates. The time and date are derived from the Avogadro constant, which is approximately , defining the number of particles (atoms or molecules) in one mole (mol) of substance, one of the seven base SI units. Overview Mole Day originated from a celebration by educator Margaret Christoph. She wrote an article about her experiences in ''The Science Teacher'' in the 1980s Inspired by this article, Maurice Oehler, a high school chemistry teacher from Prairie du Chien, Wisconsin, founded the National Mole Day Foundation (NMDF) on May 15, 1991. Many high schools around the United States, South Africa, Australia, and Canada celebrate Mole Day as a way to get their students interested in chemistry, with various activities often related to chemistry or moles. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Powerful Number
A powerful number is a positive integer ''m'' such that for every prime number ''p'' dividing ''m'', ''p''2 also divides ''m''. Equivalently, a powerful number is the product of a square and a cube, that is, a number ''m'' of the form ''m'' = ''a''2''b''3, where ''a'' and ''b'' are positive integers. Powerful numbers are also known as squareful, square-full, or 2-full. Paul Erdős and George Szekeres studied such numbers and Solomon W. Golomb named such numbers ''powerful''. The following is a list of all powerful numbers between 1 and 1000: :1, 4, 8, 9, 16, 25, 27, 32, 36, 49, 64, 72, 81, 100, 108, 121, 125, 128, 144, 169, 196, 200, 216, 225, 243, 256, 288, 289, 324, 343, 361, 392, 400, 432, 441, 484, 500, 512, 529, 576, 625, 648, 675, 676, 729, 784, 800, 841, 864, 900, 961, 968, 972, 1000, ... . Equivalence of the two definitions If ''m'' = ''a''2''b''3, then every prime in the prime factorization of ''a'' appears in the prime factorization of ''m'' with an exponent of at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odd Numbers
In mathematics, parity is the property of an integer of whether it is even or odd. An integer is even if it is a multiple of two, and odd if it is not.. For example, −4, 0, 82 are even because \begin -2 \cdot 2 &= -4 \\ 0 \cdot 2 &= 0 \\ 41 \cdot 2 &= 82 \end By contrast, −3, 5, 7, 21 are odd numbers. The above definition of parity applies only to integer numbers, hence it cannot be applied to numbers like 1/2 or 4.201. See the section "Higher mathematics" below for some extensions of the notion of parity to a larger class of "numbers" or in other more general settings. Even and odd numbers have opposite parities, e.g., 22 (even number) and 13 (odd number) have opposite parities. In particular, the parity of zero is even. Any two consecutive integers have opposite parity. A number (i.e., integer) expressed in the decimal numeral system is even or odd according to whether its last digit is even or odd. That is, if the last digit is 1, 3, 5, 7, or 9, then it is odd; otherwis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finell
Kent Finell (12 July 1944 – 27 August 2013) was a Swedish radio presenter and producer."Finell, Kent", ''Nationalencyklopedin'' bibliographical entry, retrieved 24 March 2014 He is best known for hosting the Sveriges Radio programme Svensktoppen between 1973 until 1975, from 1979 until 1980, and again from 1987 until 2002. Born in Karlstad in 1944, he joined Sveriges Radio in 1965 as a reporter. In 1969, he moved to Stockholm, where he was hired by SR as producer of the entertainment department for the radio. Since 1973, he was known for hosting radio programmes such as Svensktoppen which he hosted for 21 years between 1973 until 2002. He provided SR radio commentary for the Eurovision Song Contest between 1978 until 1980 and from 1982 until 1983 and again in 1989. Death Kent Finell died in Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countrie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root Vegetable
Root vegetables are underground plant parts eaten by humans as food. Although botany distinguishes true roots (such as taproots and tuberous roots) from non-roots (such as bulbs, corms, rhizomes, and tubers, although some contain both hypocotyl and taproot tissue), the term "root vegetable" is applied to all these types in agricultural and culinary usage (see terminology of vegetables). Potatoes are technically tubers, not roots, and sweet potatoes are tuberous roots. Root vegetables are generally storage organs, enlarged to store energy in the form of carbohydrates. They differ in the concentration and the balance among starches, sugars, and other types of carbohydrate. Of particular economic importance are those with a high carbohydrate concentration in the form of starch; starchy root vegetables are important staple foods, particularly in tropical regions, overshadowing cereals throughout much of Central Africa, West Africa and Oceania, where they are used directly or mashed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square Root
In mathematics, a square root of a number is a number such that ; in other words, a number whose ''square'' (the result of multiplying the number by itself, or ⋅ ) is . For example, 4 and −4 are square roots of 16, because . Every nonnegative real number has a unique nonnegative square root, called the ''principal square root'', which is denoted by \sqrt, where the symbol \sqrt is called the ''radical sign'' or ''radix''. For example, to express the fact that the principal square root of 9 is 3, we write \sqrt = 3. The term (or number) whose square root is being considered is known as the ''radicand''. The radicand is the number or expression underneath the radical sign, in this case 9. For nonnegative , the principal square root can also be written in exponent notation, as . Every positive number has two square roots: \sqrt, which is positive, and -\sqrt, which is negative. The two roots can be written more concisely using the ± sign as \plusmn\sqrt. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radish
The radish (''Raphanus raphanistrum'' subsp. ''sativus'') is an Eating, edible root vegetable of the family Brassicaceae that was domesticated in Asia prior to Roman Empire, Roman times. Radishes are grown and consumed throughout the world, being mostly eaten raw as a crunchy salad vegetable with a pungency, pungent, slightly spicy flavor, varying in intensity depending on its growing environment. There are numerous variety (botany), varieties, varying in size, flavor, color, and length of time they take to mature. Radishes owe their sharp flavor to the various chemical compounds produced by the plants, including glucosinolate, myrosinase, and isothiocyanate. They are sometimes grown as companion plants and suffer from few pests and diseases. They germinate quickly and grow rapidly, common smaller varieties being ready for consumption within a month, while larger ''daikon'' varieties take several months. Being easy to grow and quick to harvest, radishes are often planted by novi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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