Date: 03/11/2002 at 20:40:54 From: Marisol Subject: Symbols What do these symbols mean? ~ ! @ # $ % ^ & * ( ) - _ + = / ? I know what some are used for, but I don't know what they mean.
Date: 03/11/2002 at 22:35:50 From: Doctor Twe Subject: Re: Symbols Hi Marisol - thanks for writing to Dr. Math. Like letters of the alphabet, symbols have different meanings in different contexts or situations. I'll give you some meanings of your symbols in mathematical contexts. ~ This symbol is called a tilde. In symbolic logic (a field of math used a lot in computer sciences) it is used to denote "not." For example, ~A means "not A." In some other contexts, it means "approximately." For example, pi ~= 3.1416. (Note that sometimes it is written above the equal sign, and sometimes it is used without an equal sign - it depends on the situation and the publisher.) ! The factorial of an integer is the product of all integers below it down to one. For example, 4! = 4 x 3 x 2 x 1 = 24. @ The "at sign." This symbol generally means "at" or "each." For example, firstname.lastname@example.org is read as "doctor math at math forum dot org," while "3 pears, $.40 @" is read as "three pears, 40 cents each." # The name of this symbol is the octothorpe (most people don't know this). It is commonly called the "pound sign" or the "number sign" because that is what it is generally used to represent. 24# is read as "24 pounds," while "fax #: 1-800-555-1212" is read as "fax number 1-800-555-1212." $ The dollar sign. This usually is used to represent currency; U.S. dollars, Canadian dollars, etc. % The percent sign. Percent means "per 100" or "divided by 100." When following a number, it indicates that the number is a percentage. For example, 25% = 25 per 100 = 25/100 = 1/4 or .25. ^ The carat. In math, particularly when typing on a keyboard, this symbol can be used to indicate raised to a power. For example, 4^3 = 4 to the 3rd power = 4 x 4 x 4 = 64. & This symbol is called an ampersand. It almost always means "and," both in and outside of mathematics. * This symbol is called an asterisk. In mathematics, we sometimes use it to mean multiplication, particularly with computers. For example, 5*3 = 5 times 3 = 15. () The open (or left) and close (or right) parenthesis. In math, operations enclosed in parentheses must be done before operations outside of parentheses. Parentheses are almost always used as a pair. - The hyphen, sometimes called a dash. In math, it usually means subtraction. For example 5-3 = 5 minus 3 = 2. _ The underscore. This is sometimes used to indicate a base or subscript (especially when typing on a keyboard). For example 1001_2 means 1001 base 2 or 1001 with a subscripted 2. + The plus sign. In arithmetic, it means addition. For example, 5+3 = 8. In symbolic logic, it is used to represent "or." For example, A+B is read as "A or B." = The equals sign. This is one of several symbols that can be used to mean equals or equivalence. Some fields of math make a distinction between equal and equivalent, and use different symbols for each. / The forward slash. Often used when typing on a keyboard to represent division. For example, 8/2 = 4. I hope this helps! If you have any more questions, write back! - Doctor TWE, The Math Forum http://mathforum.org/dr.math/
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