An abacus, also called a counting frame, is a hand-operated calculating tool which was used from ancient times in the ancient Near East, Europe, China, and Russia, until the adoption of the Arabic numeral system. An abacus consists of a two-dimensional array of slidable beads. In their earliest designs, the beads could be loose on a flat surface or sliding in grooves. Later the beads were made to slide on rods and built into a frame, allowing faster manipulation.
Felix Christian Klein was a German mathematician and mathematics educator, known for his work in group theory, complex analysis, non-Euclidean geometry, and the associations between geometry and group theory. His 1872 Erlangen program classified geometries by their basic symmetry groups and was an influential synthesis of much of the mathematics of the time.
Julius Plücker was a German mathematician and physicist. He made fundamental contributions to the field of analytical geometry and was a pioneer in the investigations of cathode rays that led eventually to the discovery of the electron. He also vastly extended the study of Lamé curves.
Arnold Johannes Wilhelm Sommerfeld, was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and mentored many students for the new era of theoretical physics. He served as doctoral supervisor and postdoc supervisor to seven Nobel Prize winners and supervised at least 30 other famous physicists and chemists. Only J. J. Thomson's record of mentorship offers a comparable list of high-achieving students.
Rudolf Otto Sigismund Lipschitz was a German mathematician who made contributions to mathematical analysis and differential geometry, as well as number theory, algebras with involution and classical mechanics.
A mental calculator or human calculator is a person with a prodigious ability in some area of mental calculation.
Christian Hugo Eduard Study was a German mathematician known for work on invariant theory of ternary forms (1889) and for the study of spherical trigonometry. He is also known for contributions to space geometry, hypercomplex numbers, and criticism of early physical chemistry.
Adolf Hurwitz was a German mathematician who worked on algebra, analysis, geometry and number theory.
Carl Gottfried Neumann was a German mathematician.
The Decamentathlon is a multi disciplined games event that was created as part of the first Mind Sports Olympiad. It was founded to try to find the best games all-rounder in the world and hence possibly the best games player. It was given a prize fund of £10,000 for the inaugural competition, that equalled that of the highest funded event at the first MSO sponsored by Skandia. However, the other events were spread over multiple playing sessions whereas the Decamentathlon was held over just a single session. This event was initially hailed as the MSO flagship event. Although, the Mind Sports Olympiad's other new event the Pentamind has since become regarded as the more significant event despite not having a fixed format.
Mikhail Semyonovich Tsvet, also spelt Tsvett, Tswett, Tswet, Zwet, and Cvet was a Russian-Italian botanist who invented chromatography. His last name is Russian for "colour" and is also the root word of "flower."
Extracting the 13th root of a number is a famous category for the mental calculation world records. The challenge consists of being given a large number and asked to return the number that, when taken to the 13th power, equals the given number. For example, the 13th root of 8,192 is 2 and the 13th root of 96,889,010,407 is 7.
Ernst Klee was a German journalist and author. As a writer on Germany's history, he was best known for his exposure and documentation of medical crimes in Nazi Germany, much of which was concerned with the Action T4 or involuntary euthanasia program. He is the author of "The Good Old Days": The Holocaust Through the Eyes of the Perpetrators and Bystanders first published in the English translation in 1991.
Heinrich Franz Friedrich Tietze was an Austrian mathematician, famous for the Tietze extension theorem on functions from topological spaces to the real numbers. He also developed the Tietze transformations for group presentations, and was the first to pose the group isomorphism problem. Tietze's graph is also named after him; it describes the boundaries of a subdivision of the Möbius strip into six mutually-adjacent regions, found by Tietze as part of an extension of the four color theorem to non-orientable surfaces.
Kurt Wilhelm Sebastian Hensel was a German mathematician born in Königsberg.
Stefan Bergman was a Poland-born American mathematician whose primary work was in complex analysis. He is known for the kernel function he discovered in 1922 at University of Berlin. This function is now known as the Bergman kernel. Bergman taught for many years at Stanford University.
Willem Klein, also known as Wim Klein or under his stage names Pascal and Willy Wortel, was a Dutch mathematician, famous for being able to carry out very complicated calculations in his head very fast. On 27 August 1976, he calculated the 73rd root of a 500-digit number in 2 minutes and 43 seconds. This feat was recorded by the Guinness Book of Records.
Alexis Lemaire is a mental calculation world record holder. He holds a Ph.D. in Computer Science related to artificial intelligence from the University of Reims. He is also the owner of world records for mentally calculating the 13th root of 100-digit numbers and 200-digit numbers.
Sebastian Finsterwalder was a German mathematician and glaciologist. Acknowledged as the "father of glacier photogrammetry"; he pioneered the use of repeat photography as a temporal surveying instrument in measurement of the geology and structure of the Alps and their glacier flows. The measurement techniques he developed and the data he produced are still in use to discover evidence for climate change.
Friedrich Bachmann was a German mathematician who specialised in geometry and group theory.
