One half

One half

One half is the fraction resulting from dividing one by two, or any number by its double. It is the fraction occurring most often in mathematical equations, recipes, measurements, etc.

1/2
Binary 0.1, or
00111111000000000000000000000000
in single-precision floating point
Decimal 0.5
Hexadecimal 0.8, or 3F000000
in single-precision floating point

1/2
Binary	0.1, or 00111111000000000000000000000000 in single-precision floating point
Decimal	0.5
Hexadecimal	0.8, or 3F000000 in single-precision floating point

For instance, the area S of a triangle is computed

S = 1/2 � base � altitude

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

�n((s-2)n - (4-s))

and in the formula for computing magic constants for magic squares

M₂(n) = 1/2 * ( n ( n² + 1 ) )

One half is also:

One of the few fractions to get a key of its own on typewriters. It also gets its own point in some early extensions of ASCII at 189; and in Unicode, it gets its own code point at 189 in the C1 Controls and Latin-1 Supplement block, and a cross-reference in the Number Forms block, which contains some other fractions.

See also: List of numbers