84 (number) Overview and properties of the integer 84: factors, prime factorization, representations, combinatorial occurrences and a few notable mathematical facts.
841 — the number and the year: mathematical properties and historical notes 841 841 is the integer 29² with simple factor structure and elementary representations; as a year, 841 AD sits in the Carolingian era and saw notable conflicts among Louis the Pious’s…
842 (number and year) 842 842 is a natural number — an even semiprime and equal to 29²+1 — and also denotes the year AD 842, noted for the Oaths of Strasbourg, an early vernacular document in Western Europe…
844 (number) 844 844 is a natural number notable for its arithmetic structure (2^2·211), representations in different bases, appearance as a calendar year, and use as a toll‑free area code in North…
860 (number and year) 860 A compact encyclopedic overview of 860: its mathematical properties, numeral representations, the years 860 AD/BC, and common modern uses such as the telephone area code.
871 (number) 871 871 is an odd composite integer; a semiprime equal to 13×67. It is squarefree and deficient, with notable representations in various bases and appearance as years 871 BC and AD 871…
876 (number) 876 876 is a composite even integer (2^2·3·73). It has 12 divisors, is an abundant number, and appears in contexts such as Jamaica's telephone area code and the historical year 876 AD.
88 (number): mathematical properties, uses, and notable facts 88 (number) A concise overview of the integer 88 — its arithmetic properties, divisors and factorization, numeral representations, cultural and scientific associations, and distinguishing feat…
880 (number and common references) 880 880 is an even composite number (2^4·5·11), an abundant Harshad number and the pitch A5 (880 Hz); it is also the international telephone country code +880 for Bangladesh and denote…
882 (number) 882 882 is an even composite integer with prime factorization 2 × 3^2 × 7^2. It has 18 divisors, is abundant, φ(882)=252, equals 2·21^2 and can be written as 21^2 + 21^2.
885 (number and year) 885 Overview of 885 as an integer and a historical year: mathematical properties, numeric representations, notable facts, and the year 885 AD in context of the early medieval period.
886: Mathematical properties and key events of the year AD 886 886 Overview of 886: its math properties (even semiprime 2×443, divisors, deficient, binary/hex) and the year AD 886's notable medieval events, including the end of the Siege of Paris…
89 (number): properties, mathematical role, and notable occurrences 89 (number) An overview of the integer 89: its mathematical characteristics (prime, Fibonacci), representations, appearances in science, and a few notable facts.
9 (number) An overview of the number nine: its mathematical properties, notation and history, common uses and cultural references, and distinguishing features in arithmetic and numeration.
90 (number) An integer equal to nine times ten; an even, composite, pronic number with twelve divisors. Commonly encountered as a right angle (90°) and in many arithmetic and cultural contexts…
919: the number, the year, and common modern uses 919 An overview of 919 as an integer and palindromic prime, its place in history (AD 919), and modern associations such as the North Carolina area code and motorsport model numbers.
924 (integer): factors, divisors, abundance, and binomial coefficient C(12,6) 924 Overview of the integer 924: prime factors 2^2·3·7·11, 24 divisors, abundant (proper divisors sum 1764), φ(924)=240, and the central binomial coefficient C(12,6)=924.
980 (number) 980 An overview of the integer 980: factorization, divisors, arithmetic properties, representations in several bases, and common contexts where the number appears.
981 (number) 981 981 is an odd composite integer with prime factorization 3^2·109. This article summarizes its arithmetic properties, representations in various numeral systems, and common uses of…
984 (number and year) 984 984 is a composite even integer with prime factorization 2^3·3·41 and notable divisor and divisor-sum properties; it is also the year 984 AD in the early medieval period (Julian ca…
985 985 can mean the integer 985, the year 985 CE in the 10th century, China’s higher education Project 985, or other uses such as a telephone area code and product model numbers.
995 (number) 995 Natural number 995: mathematical properties, factorization, numeric representations, classification, and cultural references such as country calling code +995.
996: the number, historical years, and the Chinese work-schedule term 996 “996” may mean the integer 996, years labeled 996 (AD or BC), or the Chinese tech-era work schedule (9:00–21:00, six days a week). This article explains numeric properties, histori…
998 (number) 998 998 is an even three-digit integer (2 × 499). Notable as the largest even three-digit number, it is a semiprime with simple divisors and appears in numeric systems, telephony, and…
999: the number, the emergency code, and common meanings 999 Overview of 999 as a three‑digit number, its mathematical properties, history as an emergency telephone code, and other practical and cultural uses.
A Mathematician's Apology G. H. Hardy's 1940 essay defending pure mathematics, mixing autobiography, reflections on beauty and usefulness, and thoughts on the creative life of mathematicians.
A1 — Uses, meanings and notable examples A1 Overview of the alphanumeric label “A1” (also A-1, A.1.), its common senses—quality rating, paper size, roads, sauce brand, music pitch, chess square, visas and more—and its origin…
Abacus: history, design, and uses of the manual calculating frame Abacus An abacus is a manual counting device used for arithmetic, with regional forms such as the Chinese suanpan and Japanese soroban; still used for education, commerce and by visually…
ABC — the first three letters of the Latin alphabet ABC ABC are the initial three letters of the Latin alphabet; a literal sequence in writing and a widespread metaphor for fundamentals, with roots in Phoenician, Greek and Etruscan scri…
Abelian group An abelian group is a set with an associative, invertible binary operation that is commutative. This article explains its definition, examples, structure theorem for finitely gener…
Abraham de Moivre: life and mathematical contributions Abraham de Moivre French Huguenot mathematician known for probability theory, de Moivre's formula connecting complex numbers and trigonometry, contributions to the normal approximation, and an early…
Absolute truth (philosophical concept) Absolute truth An overview of absolute truth: its meaning, types (logical, mathematical, moral, empirical), historical debates, and how it differs from provisional or relative truth.
Absolute value (modulus) of a number Absolute value The absolute value of a number gives its nonnegative magnitude or distance from zero. This article explains definitions for real and complex numbers, key properties, examples, and…
Abstract algebra: structures, concepts, history and applications Abstract algebra Overview of abstract algebra: main structures (groups, rings, fields, vector spaces), key constructions, historical origins, and major applications across mathematics and science.
Abstraction: definition, types, history, and practical uses Abstraction Overview of abstraction as a process and concept: how it reduces detail to highlight essential features, its forms, history, and applications across science, engineering, art, and…
Abundant number An abundant number is an integer whose proper divisors sum to more than the number itself; contrasted with deficient and perfect numbers and related to divisor-sum functions and sp…
Ace (playing card) Ace (card) An ace denotes the single unit on a playing card, die face, or domino. Its rank and symbolism vary by game and culture — sometimes lowest, often highest — and it appears in many ru…
Actuary A professional who analyzes financial risk from uncertain events using math, probability, economics and finance to price, reserve and manage obligations for firms and institutions.
Acute angle An acute angle is an angle smaller than a right angle (0°–90°). Covers definition, properties, measurement, examples such as acute triangles, historical notes, and distinctions fro…
Adam Ries (Adam Riese) — German arithmetician and author Adam Ries Sixteenth-century German mathematician known for practical arithmetic books in the vernacular, promotion of Hindu–Arabic numerals, and lasting influence on commercial calculation a…
Addition (mathematics) Addition Addition is the basic arithmetic operation of combining quantities to form a sum. It applies to numbers, vectors, matrices and abstract algebraic structures and has key properties…
Adjacent: meaning and uses in geometry, trigonometry, and everyday contexts Adjacent Clear explanation of 'adjacent' as 'next to', with mathematical definitions (geometry, trigonometry, graph theory), common uses, distinctions from related terms, and simple example…
Alan Baker (mathematician): transcendental number theory and Diophantine methods Alan Baker (mathematician) Alan Baker (1939–2018), English mathematician noted for Baker's theorem on linear forms in logarithms, effective results in Diophantine equations, Fields Medal 1970, FRS and AMS fe…
Albrecht Böttcher — German mathematician in functional analysis and operator theory Albrecht Böttcher Profile of Albrecht Böttcher, a German mathematician known for work in functional analysis, operator theory and numerical methods for integral and operator equations; education, ca…
Aleph null (ℵ0): the smallest infinite cardinal Aleph null Aleph null (ℵ0) denotes the cardinality of the natural numbers: the first infinite cardinal. This article explains its meaning, examples, basic properties, history and key distinct…
Aleph one (ℵ1): the first uncountable cardinal Aleph one Aleph one (ℵ1) is the smallest uncountable cardinal, the cardinality of the set of all countable ordinals (ω1). It follows ℵ0 and plays a central role in the continuum hypothesis a…
Algebra: concepts, notation, history, branches and applications Algebra Overview of algebra: fundamentals, notation, common problem types (linear, quadratic), historical origins, branches (elementary, linear, abstract) and practical applications across…
Algebraic equation An algebraic equation equates two polynomials over a specified coefficient domain. This article covers definitions, degrees and roots, solution fields, historical milestones, metho…
