Multiplication sign
The multiplication sign, also known as the times sign or the dimension sign, is the symbol. While similar to a lowercase X, the form is properly a rotationally symmetric saltire.
History
The multiplication sign, although often attributed to William Oughtred, apparently had been in occasional use since the mid 16th century.Uses
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"
- 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"
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".
A monadic symbol is used by the APL programming language to denote the sign function.
Similar notations
The lower-case Latin letter 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: " multiplied by " can be written as or.
Other symbols can also be used to denote multiplication, often to reduce confusion between the multiplication sign × and the common variable. In some countries, such as Germany, the primary symbol for multiplication is as in . This symbol is also used in algebraic notation to resolve ambiguity, for instance "b times 2" may be written to avoid being confused with a value called. This notation is used wherever multiplication should be written explicitly, such as in " for "; this usage is also seen in English-language texts. In some languages, the use of full stop as a multiplication symbol, such as, is common when the symbol for decimal point is comma.
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
| HTML, SGML, XML | & or & |
| macOS | In the Character Palette by searching for MULTIPLICATION SIGN |
| Microsoft Windows |
|
| OpenOffice.org | times |
| TeX | \times |
| Unix-like |