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Mathematics is the study of representing and reasoning about abstract objects (such as numbers, points, spaces, sets, structures, and games). Mathematics is used throughout the world as an essential tool in many fields, including natural science, engineering, medicine, and the social sciences. Applied mathematics, the branch of mathematics concerned with application of mathematical knowledge to other fields, inspires and makes use of new mathematical discoveries and sometimes leads to the development of entirely new mathematical disciplines, such as statistics and game theory. Mathematicians also engage in pure mathematics, or mathematics for its own sake, without having any application in mind. There is no clear line separating pure and applied mathematics, and practical applications for what began as pure mathematics are often discovered. (Full article...)

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animation of a grid of boxes numbered 2 through 120, where the prime numbers are progressively circled and listed to the side while the composite numbers are struck out
animation of a grid of boxes numbered 2 through 120, where the prime numbers are progressively circled and listed to the side while the composite numbers are struck out
The sieve of Eratosthenes is a simple algorithm for finding all prime numbers up to a specified maximum value. It works by identifying the prime numbers in increasing order while removing from consideration composite numbers that are multiples of each prime. This animation shows the process of finding all primes no greater than 120. The algorithm begins by identifying 2 as the first prime number and then crossing out every multiple of 2 up to 120. The next available number, 3, is the next prime number, so then every multiple of 3 is crossed out. (In this version of the algorithm, 6 is not crossed out again since it was just identified as a multiple of 2. The same optimization is used for all subsequent steps of the process: given a prime p, only multiples no less than p2 are considered for crossing out, since any lower multiples must already have been identified as multiples of smaller primes. Larger multiples that just happen to already be crossed out—like 12 when considering multiples of 3—are crossed out again, because checking for such duplicates would impose an unnecessary speed penalty on any real-world implementation of the algorithm.) The next remaining number, 5, is the next prime, so its multiples get crossed out (starting with 25); and so on. The process continues until no more composite numbers could possibly be left in the list (i.e., when the square of the next prime exceeds the specified maximum). The remaining numbers (here starting with 11) are all prime. Note that this procedure is easily extended to find primes in any given arithmetic progression. One of several prime number sieves, this ancient algorithm was attributed to the Greek mathematician Eratosthenes (d. c. 194 BCE) by Nicomachus in his first-century (CE) work Introduction to Arithmetic. Other more modern sieves include the sieve of Sundaram (1934) and the sieve of Atkin (2003). The main benefit of sieve methods is the avoidance of costly primality tests (or, conversely, divisibility tests). Their main drawback is their restriction to specific ranges of numbers, which makes this type of method inappropriate for applications requiring very large prime numbers, such as public-key cryptography.

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  • ... that in 1940 Xu Ruiyun became the first Chinese woman to receive a PhD in mathematics?
  • ... that circle packings in the form of a Doyle spiral were used to model plant growth long before their mathematical investigation by Doyle?
  • ... that the mathematical infinity symbol ∞ may be derived from the Roman numerals for 1000 or for 100 million?
  • ... that The Math Myth advocates for American high schools to stop requiring advanced algebra?
  • ... that Donn Piatt threw his mathematics teacher out of the window?
  • ... that Catechumen, a Christian first-person shooter, was funded only in the aftermath of the Columbine High School massacre?
  • ... that Arithmetic was the first mathematics text book written in the Russian language?
  • ... that ten-sided gaming dice have kite-shaped faces?

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  • ...the Piphilology record (memorizing digits of Pi) is 70000 as of Mar 2015?
  • ...that people are significantly slower to identify the parity of zero than other whole numbers, regardless of age, language spoken, or whether the symbol or word for zero is used?
  • ...that Auction theory was successfully used in 1994 to sell FCC airwave spectrum, in a financial application of game theory?
  • ...properties of Pascal's triangle have application in many fields of mathematics including combinatorics, algebra, calculus and geometry?
  • ...work in artificial intelligence makes use of swarm intelligence, which has foundations in the behavioral examples found in nature of ants, birds, bees, and fish among others?
  • ...that statistical properties dictated by Benford's Law are used in auditing of financial accounts as one means of detecting fraud?
  • ...that modular arithmetic has application in at least ten different fields of study, including the arts, computer science, and chemistry in addition to mathematics?
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Dodecahedron
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A Platonic solid is a convex regular polyhedron. These are the three-dimensional analogs of the convex regular polygons. There are precisely five such figures (shown on the left). The name of each figure is derived from the number of its faces: respectively 4, 6, 8, 12 and 20. They are unique in that the sides, edges and angles are all congruent.
Due to their aesthetic beauty and symmetry, the Platonic solids have been a favorite subject of geometers for thousands of years. They are named after the ancient Greek philosopher Plato who claimed the classical elements were constructed from the regular solids.
The Platonic solids have been known since antiquity. The five solids were certainly known to the ancient Greeks and there is evidence that these figures were known long before then. The neolithic people of Scotland constructed stone models of all five solids at least 1000 years before Plato. (Full article...)

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  1. ^ Galambos & Woeginger (1995); Brown (1979); Liang (1980).