# 2015 Top Ten of Conflict for Mathematics

42 (number)
42 (forty-two) is the natural number that follows 41 and precedes 43
Name
A name is a term used for identification by an external observer. They can identify a class or category of things, or a single thing, either uniquely, or within a given context. The entity identified by a name is called its referent. A personal name identifies, not necessarily uniquely, a specific individual human. The name of a specific entity is sometimes called a proper name and is, when consisting of only one word, a proper noun. Other nouns are sometimes called "common names" or (obsolete) "general
666 (number)
666 is the natural number following 665 and preceding 667
2 + 2 = 5
The mathematically incorrect phrase "two plus two equals five" is best known in English for its use in the 1949 dystopian novel Nineteen Eighty-Four by George Orwell, as a possible statement of Ingsoc philosophy, like the dogma "War is Peace", which the Party expects the citizens of Oceania to believe is true. In writing his secret diary in the year 1984, the protagonist Winston Smith ponders if the Inner Party might declare that "two plus two equals five" is a fact. Smith further ponders whether or not
Speed of light
The speed of light in vacuum, commonly denoted c, is a universal physical constant that is important in many areas of physics. Its exact value is defined as 299792458 metres per second. It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time interval of 1⁄299792458 second. According to special relativity, c is the upper limit for the speed at which conventional matter, energy or any signal carrying information can travel
Circle
A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre; equivalently it is the curve traced out by a point that moves in a plane so that its distance from a given point is constant. The distance between any point of the circle and the centre is called the radius. Usually, the radius is required to be a positive number. This article is about circles in Euclidean geometry, and, in particular, the Euclidean plane, except where otherwise noted
Calculus
Calculus, originally called infinitesimal calculus or "the calculus of infinitesimals", is the mathematical study of continuous change, in the same way that geometry is the study of shape and algebra is the study of generalizations of arithmetic operations
Names of large numbers
This article lists and discusses the usage and derivation of names of large numbers, together with their possible extensions
Integer
An integer is colloquially defined as a number that can be written without a fractional component. For example, 21, 4, 0, and −2048 are integers, while 9.75, 5+1/2, and √2 are not
Binary number
A binary number is a number expressed in the base-2 numeral system or binary numeral system, a method of mathematical expression which uses only two symbols: typically "0" (zero) and "1" (one