
In Unicode, it has its own code unit at U+00BD (decimal 189) in the C1 Controls and Latin-1 Supplement block and a cross-reference in the Number Forms block, rendering as "½." It also has its own code point in some early extensions of ASCII at 171. Postal stamp, Ireland, 1940: one halfpenny postage due.ġ⁄ 2 is also one of the few fractions to usually have a key of its own on typewriters (see fractions). In odd bases, one half has no terminating representation, only a single representation with a repeating fractional component, such as 0.11111111.

equals 1 for a detailed discussion of a related case. It is common to believe these expressions represent distinct numbers: see the proof that 0.999. It has a similar pair of expansions in any even base. One half has two different decimal expansions, the familiar 0.5 and the recurring 0.49999999. The Riemann hypothesis states that every nontrivial complex root of the Riemann zeta function has a real part equal to 1 / 2. One half also figures in the formula for calculating figurate numbers, such as triangular numbers and pentagonal numbers:

Half can also be said to be one part of something divided into two equal parts.įor instance, the area S of a triangle is computed.

One half often appears in mathematical equations, recipes, measurements, etc. 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 is the irreducible fraction resulting from dividing one by two (2) or the fraction resulting from dividing any number by its double.
