Associated Topics || Dr. Math Home || Search Dr. Math

### Math Symbols

```
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, dr.math@mathforum.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.

%  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/
```
Associated Topics: