Multiplication sign
This article needs additional citations for verification. (January 2017) (Learn how and when to remove this template message) 
×  

Multiplication sign  
In Unicode  U+00D7 × MULTIPLICATION SIGN (HTML × · × ) 
Related  
See also  U+2715 ✕ MULTIPLICATION X U+22C5 ⋅ DOT OPERATOR U+00F7 ÷ DIVISION SIGN 
Different from  
Different from  U+0078 x LATIN SMALL LETTER X (HTML x ) 
The multiplication sign, also known as the times sign or the dimension sign, is the symbol ×. While similar to a lowercase X (x), the form is properly a rotationally symmetric saltire.^{[1]}
History[edit]
The multiplication sign ×, although often attributed to William Oughtred (who first used it in an appendix to the 1618 edition of John Napier's Mirifici Logarithmorum Canonis Descriptio), apparently had been in occasional use since the mid 16th century.^{[2]}
Uses[edit]
In mathematics, the symbol × has a number of uses, including
 Multiplication of two scalar numbers, where it is read as "times" or "multiplied by"
 Cross product of two vectors, where it is usually read as "cross"
 Cartesian product of two sets, where it is usually read as "cross"
 Geometric dimension of an object, such as noting that a room is 10 feet × 12 feet in area, where it is usually read as "by" (for example: "10 feet by 12 feet")
 Dimensions of a matrix, where it is usually read as "by"
 A statistical interaction between two explanatory variables, where it is usually read as "by"
In biology, the multiplication sign is used in a botanical hybrid name, for instance Ceanothus papillosus × impressus (a hybrid between C. papillosus and C. impressus) or Crocosmia × crocosmiiflora (a hybrid between two other species of Crocosmia). However, the communication of these hybrid names with a Latin letter "x" is common when the actual "×" symbol is not readily available.
The multiplication sign is also used by historians for an event between two dates. When employed between two dates – for example 1225 and 1232 – the expression "1225×1232" means "no earlier than 1225 and no later than 1232".^{[3]}
A monadic × symbol is used by the APL programming language to denote the sign function.
Similar notations[edit]
The lowercase Latin letter x is sometimes used in place of the multiplication sign. This is considered incorrect in mathematical writing.
In algebraic notation, widely used in mathematics, a multiplication symbol is usually omitted wherever it would not cause confusion: "a multiplied by b" can be written as ab or a b.
Other symbols can also be used to denote multiplication, often to reduce confusion between the multiplication sign × and the common variable x. In many nonAnglophone countries the primary symbol for multiplication is ⋅ (the "dot operator") as in a⋅b. This symbol is also used in algebraic notation to resolve ambiguity, for instance "b times 2" may be written b⋅2 to avoid being confused with a value called b_{2}. This notation is used wherever multiplication should be written explicitly, such as in "ab = a⋅2 for b = 2"; this usage is also seen in Englishlanguage texts. In some languages, the use of full stop as a multiplication symbol, such as a.b, is common.
Historically, computer language syntax was restricted to the ASCII character set and the asterisk * became the de facto symbol for the multiplication operator. This selection is reflected in the standard numeric keypad, where the arithmetic operations of addition, subtraction, multiplication and division are represented by the keys +, , * and /, respectively.
Typing the character[edit]
HTML, SGML, XML  × or ×

macOS  In the Character Palette by searching for MULTIPLICATION SIGN^{[4]}^{[5]} 
Microsoft Windows 

OpenOffice.org  times 
TeX  \times

Unixlike (Linux, Chrome OS) 

Unicode and HTML entities[edit]
 U+00D7 × MULTIPLICATION SIGN (HTML
×
·×
)
Other variants and related characters:
 U+002A * ASTERISK (HTML
*
)  U+2062 INVISIBLE TIMES (HTML
⁢
) (a zerowidth space indicating multiplication)  U+00B7 · MIDDLE DOT (HTML
·
··
) (the interpunct, may be easier to type than the dot operator)  U+2297 ⊗ CIRCLED TIMES (HTML
⊗
·⊗
)  U+22C5 ⋅ DOT OPERATOR (HTML
⋅
·⋅
)  U+2715 ✕ MULTIPLICATION X (HTML
✕
)  U+2716 ✖ HEAVY MULTIPLICATION X (HTML
✖
)  U+2A09 ⨉ NARY TIMES OPERATOR (HTML
⨉
)  U+2A2F ⨯ VECTOR OR CROSS PRODUCT (HTML
⨯
) (intended to explicitly denote the cross product of two vectors)  U+2A30 ⨰ MULTIPLICATION SIGN WITH DOT ABOVE (HTML
⨰
)  U+2A31 ⨱ MULTIPLICATION SIGN WITH UNDERBAR (HTML
⨱
)  U+2A34 ⨴ MULTIPLICATION SIGN IN LEFT HALF CIRCLE (HTML
⨴
)  U+2A35 ⨵ MULTIPLICATION SIGN IN RIGHT HALF CIRCLE (HTML
⨵
)  U+2A36 ⨶ CIRCLED MULTIPLICATION SIGN WITH CIRCUMFLEX ACCENT (HTML
⨶
)  U+2A37 ⨷ MULTIPLICATION SIGN IN DOUBLE CIRCLE (HTML
⨷
)  U+2A3B ⨻ MULTIPLICATION SIGN IN TRIANGLE (HTML
⨻
)  U+2AC1 ⫁ SUBSET WITH MULTIPLICATION SIGN BELOW (HTML
⫁
)  U+2AC2 ⫂ SUPERSET WITH MULTIPLICATION SIGN BELOW (HTML
⫂
)
See also[edit]
References[edit]
 ^ Stallings, L. (2000). "A Brief History of Algebraic Notation". School Science and Mathematics. 100 (5): 230–235. doi:10.1111/j.19498594.2000.tb17262.x. ISSN 00366803.
 ^ Florian Cajori (1929). A History of Mathematical Notations. Dover Books on Mathematics. Dover. p. 251f. ISBN 9780486677668.
 ^ New Hart's rules: the handbook of style for writers and editors, Oxford University Press, 2005, p. 183, ISBN 9780198610410
 ^ "Archived copy". Archived from the original on 20100109. Retrieved 20091009.CS1 maint: archived copy as title (link)
 ^ "Archived copy". Archived from the original on 20071025. Retrieved 20091009.CS1 maint: archived copy as title (link)
 ^ "Unicode Character 'MULTIPLICATION SIGN' (U+00D7)". Fileformat.info. Retrieved 20170113.
External links[edit]
 "Letter Database". Eki.ee. Retrieved 20170113.
 "Unicode Character 'MULTIPLICATION SIGN' (U+00D7)". Fileformat.info. Retrieved 20170113.
 "Unicode Character 'VECTOR OR CROSS PRODUCT' (U+2A2F)". Fileformat.info. Retrieved 20170113.