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One half

From Wikipedia, the free encyclopedia
For the computer virus, seeOneHalf.
"Half" redirects here. For other uses, seeHalf (disambiguation).
Irreducible fraction
Look upone half in Wiktionary, the free dictionary.
Natural number
← −0.50.51.5 →
Cardinalone half
Ordinal12th (halfth)
Binary0.12
Ternary0.11111111113
Senary0.36
Octal0.48
Duodecimal0.612
Hexadecimal0.816
Greek
Roman numeralsS
Egyptian hieroglyph𓐛
Hebrewחֵצִ
Malayalam
Chinese
Tibetan

One half is themultiplicative inverse of2. It is anirreducible fraction with a numerator of 1 and a denominator of 2. It often appears inmathematical equations,recipes andmeasurements.

As a word

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One half is one of the few fractions which are commonly expressed in naturallanguages bysuppletion rather than regular derivation. InEnglish, for example, compare thecompound "one half" with other regular formations like "one-sixth".

Ahalf can also be said to be one part of something divided into two equal parts. It is acceptable to write one half as ahyphenated word,one-half.

Mathematics

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One half is therational number that lies midway between 0 and 1 on thenumber line.Multiplication by one half is equivalent todivision by two, or "halving"; conversely, division by one half is equivalent to multiplication by two, or "doubling".

Asquare of side lengthone, here dissected intorectangles whoseareas are successivepowers ofone half.

A number raised to thepower of one half is equal to itssquare root.

The area of atriangle is one half itsbase andaltitude (or height).

Fundamental region of the modularj-invariant in theupper half-plane (shadedgray), withmodular discriminant|τ|1{\displaystyle |\tau |\geq 1} and12<R(τ)12{\displaystyle -{\tfrac {1}{2}}<{\mathfrak {R}}(\tau )\leq {\tfrac {1}{2}}}, where12<R(τ)<0|τ|>1.{\displaystyle -{\tfrac {1}{2}}<{\mathfrak {R}}(\tau )<0\Rightarrow |\tau |>1.}

Thegamma function evaluated at one half is the square root ofpi.

It has two differentdecimal representations inbase ten, the familiar0.5{\displaystyle 0.5} and therecurring0.49¯{\displaystyle 0.4{\overline {9}}}[dubiousdiscuss], with a similar pair of expansions in any evenbase; while in odd bases, one half has noterminating representation.

TheBernoulli numberB1{\displaystyle B_{1}} has the value±12{\displaystyle \pm {\tfrac {1}{2}}} (its sign depending on competing conventions).

TheRiemann hypothesis is the conjecture that every nontrivialcomplex root of theRiemann zeta function has a real part equal to12{\displaystyle {\tfrac {1}{2}}}.

Computer characters

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½
In UnicodeU+00BD ½VULGAR FRACTION ONE HALF
Related
See alsoU+00BC ¼VULGAR FRACTION ONE QUARTER
U+00BE ¾VULGAR FRACTION THREE QUARTERS

The "one-half" symbol has its owncode point as aprecomposed character in theLatin-1 Supplement block ofUnicode, rendering as½.

The reduced size of this symbol may make it illegible to readers with relatively mildvisual impairment; consequently the decomposed forms12 or1/2 may be more appropriate.

See also

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Postal stamp, Ireland, 1940: one halfpenny postage due.

References

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Division and ratio
The ratio of width to height of standard-definition television.
Fraction
  • Numerator/Denominator = Quotient
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