The Mathematical Symbol "Asterisk Operator (∗)"

The ∗ Symbol in Mathematics: The Asterisk Operator

The ∗ symbol, commonly recognized as an asterisk, serves various purposes in mathematics and adjacent fields. Often called the "Asterisk Operator", its application ranges from conventional multiplication to more specialized uses in different mathematical contexts. This article delves into two primary uses of the asterisk operator, accompanied by two illustrative examples for each category.

1. Standard Arithmetic

Within arithmetic and elementary mathematics, the ∗ typically symbolizes multiplication.

  • Example 1: When denoting the multiplication of 5 and 4, one could represent it as \(5 ∗ 4 = 20\).
  • Example 2: Multiplying two variables, such as \(a\) and \(b\), can be illustrated as \(a ∗ b\).

2. Advanced Mathematical Contexts

Beyond elementary arithmetic, the asterisk assumes various roles in specialized areas of mathematics.

  • Example 1: In function analysis, the asterisk can denote the convolution of two functions. If \(f\) and \(g\) are functions, their convolution might be denoted as \(f ∗ g\).
  • Example 2: In complex conjugation, the asterisk signifies the complex conjugate of a number. For instance, if \(z\) is a complex number, its conjugate could be represented as \(z^∗\).

In summary, the ∗ symbol is versatile within the mathematical realm, marking operations from basic multiplication to specialized applications in advanced topics. Recognizing its context is vital to understand its intended use.

Mathematical symbol 'Asterisk Operator'

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Codes for the ∗ Symbol

The Symbol
Alt CodeAlt 8727
HTML Code∗
HTML Entity∗
CSS Code\2217
Hex Code∗

How To Insert the ∗ Symbol

(Method 1) Copy and paste the symbol.

The easiest way to get the ∗ symbol is to copy and paste it into your document.

Bear in mind that this is a UTF-8 encoded character. It must be encoded as UTF-8 at all stages (copying, replacing, editing, pasting), otherwise it will render as random characters or the dreaded �.

(Method 2) Use the "Alt Code."

If you have a keyboard with a numeric pad, you can use this method. Simply hold down the Alt key and type 8727. When you lift the Alt key, the symbol appears. ("Num Lock" must be on.)

(Method 3) Use the HTML Decimal Code (for webpages).

HTML TextOutput
<b>My symbol: &#8727;</b>My symbol: ∗

(Method 4) Use the HTML Entity Code (for webpages).

HTML TextOutput
<b>My symbol: &lowast;</b>My symbol: ∗

(Method 5) Use the CSS Code (for webpages).

CSS and HTML TextOutput
span:after {
content: "\2217";}
<span>My symbol:</span>
My symbol: ∗

(Method 6) Use the HTML Hex Code (for webpages and HTML canvas).

HTML TextOutput
<b>My symbol: &#x2217;</b>My symbol: ∗
On the assumption that you already have your canvas and the context set up, use the Hex code in the format 0x2217 to place the ∗ symbol on your canvas. For example:
JavaScript Text
const x = "0x"+"E9"
ctx.fillText(String.fromCodePoint(x), 5, 5);

(Method 7) Use the Unicode (for various, e.g. Microsoft Office, JavaScript, Perl).

The Unicode for ∗ is U+2217. The important part is the hexadecimal number after the U+, which is used in various formats. For example, in Microsoft Office applications (e.g. Word, PowerPoint), do the following:
[Hold down Alt]
[Press x]

(The 2217 turns into ∗. Note that you can omit any leading zeros.)
In JavaScript, the syntax is \uXXXX. So, our example would be \u2217. (Note that the format is 4 hexadecimal characters.)
JavaScript TextOutput
let str = "\u2217"
document.write("My symbol: " + str)
My symbol: ∗