Plus and minus signsCategory:Arithmetic The plus (+) and minus (−) signs are used universally to represent the operations of addition and subtraction, and have been extended to many other meanings, more or less analogous. Though the signs now seem as familiar as the alphabet or the Hindu-Arabic numerals, they are not of great antiquity. The Egyptian hieroglyphic sign for addition, for example, resembled a pair of legs walking in the direction in which the text was written, with the reverse sign indicating subtraction. In Europe in the early 15th century the letters P and M were generally used. The earliest appearance of the modern signs seems to come from a book by Johannes Widman in 1489. The + is a simplification of the Latin "et" (comparable to the ampersand &). The − may be derived from a tilde written over m when used to indicate subtraction; or it may come from a shorthand version of the letter m itself. The plus sign can mean many different operations, depending on the mathematical system under consideration. Many algebraic structures have some operation which is called, or equivalent to, addition. Moreover, the symbolism has been extended to very different operations, such as concatenation of strings of characters. Plus can mean:\n* exclusive or (usually written ⊕): 1+1=0\n* logical conjunction (usually written ∧): 1+1=1\n* logical disjunction (usually written ∨): 1+1=1\n* concatenation of string literals is sometimes written: "1"+"1"="11"
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