Multiplication sign
The multiplication sign is the symbol ×. The symbol is similar to the lowercase letter x but is a more symmetric saltire, and has different uses. It is also known as St. Andrew's Cross[1] and as the dimension sign.
In mathematics, the symbol × (read as times, multiplication sign or into sign) is primarily used to denote the
- multiplication of two numbers (computer languages bound to the rudimentary ASCII set often use an asterisk (*) to replace the missing crosses (×) and dots (·)
- cross product of two vectors
- Cartesian product of two sets
- multiplication and the sign function, as an APL operator.
The × symbol for multiplication was introduced by William Oughtred in 1631.[2] It was chosen for religious reason to represent the cross.[3] The symbol is encoded in Unicode at U+00D7 × multiplication sign (HTML: × ×).
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[edit] Similar notations
Many other symbols are used to denote multiplication, often to reduce confusion between the multiplication sign × and the commonly used variable x. Nonetheless, the letter "x" is sometimes mistakenly used in place of the multiplication sign.[4]
In many non-Anglophone countries, the · (middle dot or interpunct) is the primary multiplication sign (instead of ×): "a multiplied by b" is written either explicitly as a·b or implicitly as ab depending on context.
In biology, the multiplication sign is used in a botanical hybrid name, where it is read as "cross".
[edit] In computer software
The × symbol is listed in Unicode letterlike symbols and is U+00D7 in Unicode. It can be invoked in various operating systems as per the table below.
There is a similar character ⨯ at U+2A2F, but this is not always considered identical to U+00D7, as it is intended to explicitly denote the cross product of two vectors.
In computers, the * symbol is used most often for multiplication since the ⨯ symbol does not exist on most keyboards.
| Apple Macintosh | in Character Palette, search for MULTIPLICATION SIGN[5][6] |
| HTML | × and × |
| Microsoft Windows |
|
| Microsoft Word | U+00D7[citation needed] |
| Linux/X Window |
|
| OpenOffice.org | times |
| TeX | \times |
| Unicode | U+00D7 |
| XML | unknown |
[edit] See also
[edit] References
- ^ Stallings, L. (2000). "A Brief History of Algebraic Notation". School Science and Mathematics 100 (5): 230–235. doi:10.1111/j.1949-8594.2000.tb17262.x. ISSN 00366803.
- ^ Florian Cajori (1919). A History of Mathematics. Macmillan. http://books.google.com/?id=bBoPAAAAIAAJ&pg=PA157&dq=inauthor:cajori+william-oughtred+multiplication.
- ^ Stallings, L. (2000). "A Brief History of Algebraic Notation". School Science and Mathematics 100 (5): 230–235. doi:10.1111/j.1949-8594.2000.tb17262.x. ISSN 00366803.
- ^ David Spencer (15 February 2011). "Typographic Train Wrecks". Type Desk. Matador. http://typedesk.com/2011/01/31/typographic-train-wrecks/. Retrieved 31 January 2011.
- ^ http://www.apple.com/de/pro/tips/specialchar.html Apple Sonderzeichen (German / Deutsch)
- ^ http://www.typografie.info/typowiki/index.php?title=Mac_Zeichenpalette
- ^ http://www.fileformat.info/info/unicode/char/00D7/index.htm
[edit] External links
- http://www.eki.ee/letter/chardata.cgi?ucode=00D7
- http://www.fileformat.info/info/unicode/char/00d7/index.htm (the general multiplication sign)
- http://www.fileformat.info/info/unicode/char/2a2f/index.htm (the cross product sign)
