One half

One half is the irreducible fraction resulting from dividing one by two (¹⁄₂), or the fraction resulting from dividing any number by its double. Multiplication by one half is equivalent to division by two, or halving; conversely, division by one half is equivalent to multiplication by two, or "doubling". One half appears often in mathematical equations, recipes, measurements, etc. Half can also be said to be one part of something divided into two equal parts.

For instance, the area S of a triangle is computed

One half also figures in the formula for calculating figurate numbers, such as triangular numbers and pentagonal numbers:

and in the formula for computing magic constants for magic squares

The Riemann hypothesis states that every nontrivial complex root of the Riemann zeta function has a real part equal to ¹⁄₂.

One half has two different decimal expansions, the familiar 0.5 and the recurring 0.49999999... It has a similar pair of expansions in any even base. It is a common trap to believe these expressions represent distinct numbers: see the proof that 0.999... equals 1 for detailed discussion of a related case. In odd bases, one half has no terminating representation, only a single representation with a repeating fractional component, such as 0.11111111... in ternary.

Eton College

Eton College, often informally referred to simply as Eton, is an English boys' independent boarding school located in Eton, Berkshire, near Windsor. It educates over 1,300 pupils, aged 13 to 18 years. It was founded in 1440 by King Henry VI as "The King's College of Our Lady of Eton besides Wyndsor", making it the 18th oldest Headmasters' and Headmistresses' Conference (HMC) school.

Eton is one of ten English HMC schools, commonly referred to as "public schools", regulated by the Public Schools Act of 1868. Following the public school tradition, Eton is a full boarding school, which means all pupils live at the school, and it is one of four such remaining single-sex boys' public schools in the United Kingdom (the others being Harrow, Radley, and Winchester) to continue this practice. Eton has educated 19 British prime ministers and generations of the aristocracy and has been referred to as the chief nurse of England's statesmen. Charging up to £11,478 per term (there are three terms per academic year) in 2014/15, Eton is the sixth most expensive HMC boarding school in the UK.

Half (disambiguation)

Half may refer to: