Eight

Eight is the integer that follows seven and precedes nine. In Hindu-Arabic numerals it is written as 8; in Roman numerals as VIII; in binary notation as 1000. It is the third power of two, since 8 = 2^3, and it is an even, composite number.

The English word eight comes from Old English eahta, with cognates in many Germanic languages (for example German acht, Dutch acht, Swedish åtta, Danish otte, Norwegian åtte). The prefix octo- in Latinized and Greek-derived terms such as octagon, octahedron, and octave also reflects the eight-root etymology.

In mathematics, eight is a cube number and has divisors 1, 2, 4, and 8. Geometrically, figures associated with eight include the cube, which has eight vertices, and the regular octahedron, which has eight faces. The concept of an eightfold system appears in various counting and organizational schemes, such as octets in computing and groups of eight in music and optics.

In science and technology, oxygen has atomic number 8. In computing, a byte commonly consists of eight bits, and the octal numeral system uses base 8. Many color representations use 8 bits per channel in 24-bit color.

Culturally, eight is considered lucky in some East Asian traditions, notably in China, where it is associated with prosperity and good fortune. The solar system is commonly described as having eight planets, and in Western music an octave spans eight notes.