Division sign
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The division sign (Template:Char) is a mathematical symbol consisting of a short horizontal line with a dot above and another dot below, used in Anglophone countries to indicate the operation of division. This usage is not universal and the symbol has different meanings in other countries. Consequently, its use to denote division is deprecated in the ISO 80000-2 standard for notations used in mathematics, science and technology.<ref name=ISO /> In older textbooks, it is called an obelus, though that term is also used of other symbols.
In mathematics
The obelus, a historical glyph consisting of a horizontal line with (or without) one or more dots, was first used as a symbol for division in 1659, in the algebra book Template:Lang by Johann Rahn, although previous writers had used the same symbol for subtraction.<ref name="Cajori">Template:Cite book pp 270,271 </ref> Some near-contemporaries believed that John Pell, who edited the book, may have been responsible for this use of the symbol.<ref name="Cajori" /> Other symbols for division include the slash or solidus Template:Char, the colon Template:Char, and the fraction bar (the horizontal bar in a vertical fraction).<ref>Template:Cite web</ref><ref>Template:Cite web</ref> The ISO 80000-2 standard for mathematical notation in science and technology recommends only the solidus Template:Char or "fraction bar" for division, or the "colon" Template:Char for ratios; it says that the Template:Char sign "should not be used" for division.<ref name=ISO>BS ISO 80000-2, "Quantities and units Part 2: Mathematical signs and symbols to be used in the natural sciences and technology", Section 9 "Operations", 2-9.6</ref>
In Italy, Poland and Russia, the same Template:Char sign was sometimes used to denote a range of values, and in Scandinavian countries it was, and sometimes still is, used as a negation sign:<ref>Template:Cite book</ref> the Unicode Consortium has allocated a separate code point, Template:Unichar for this usage uniquely;<ref name=Silli1>Template:Cite web</ref><ref name=Silli2>Template:Cite web</ref> the exact form of the symbol displayed is typeface (font) dependent.
In computer systems
Encoding
The symbol was assigned to code point 0xF7 in ISO 8859-1, as the "division sign". This encoding was transferred to Unicode as U+00F7.<ref>Template:Citation</ref> In HTML, it can be encoded as Template:Code or Template:Code (at HTML level 3.2), or as Template:Code.
Unicode provides various division symbols:<ref>Template:Cite web</ref>
| Codepoint | Name | Symbol |
|---|---|---|
| U+00F7 | Division Sign | ÷ |
| U+27CC | Long Division | ⟌ |
| U+2215 | Division Slash | ∕ |
| U+2A38 | Circled Division Sign | ⨸ |
| U+2797 | Heavy Division Sign | ➗ |
| U+2298 | Circled Division Slash | ⊘ |
| U+22C7 | Division Times | ⋇ |
| U+29BC | Circled Anticlockwise-Rotated Division Sign | ⦼ |
Use
Most programming languages use only the printable and whitespace ASCII characters, and so do not use the ÷ character. However, the programming language APL uses ÷ for the unary reciprocal operator and the binary division operator.