The Mathematical Symbol "Infinity (∞)"

The ∞ Symbol in Mathematics: Infinity

Throughout the vast landscape of mathematics, some symbols resonate profoundly due to their universal significance. One such symbol is ∞, emblematic of the concept of infinity.

Usage

The ∞ symbol represents the idea of an unbounded, limitless quantity. This concept transcends the bounds of finite numbers and finds applications in various mathematical fields such as calculus, set theory, and topology, among others.

Examples

  • Example 1: Limits:
    In calculus, the limit of a function as it approaches a particular point might be infinite. For instance, the limit of \( \frac{1}{x} \) as \( x \) approaches 0 from the right is ∞.
  • Example 2: Cardinality:
    In set theory, the cardinality (or size) of the set of all natural numbers is represented by ∞, signifying an infinite set.
  • Example 3: Geometry and Topology:
    The concept of a "point at infinity" is employed in projective geometry, where parallel lines are said to meet at this point, symbolized by ∞.

To conclude, the ∞ symbol serves as a powerful representation of the boundless and immeasurable. Its usage permeates various domains of mathematics, from the intricacies of set theory to the intuitive grasp of calculus, echoing the vastness and potential of mathematical exploration.

Mathematical symbol 'Infinity'

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Codes for the ∞ Symbol

The Symbol∞
Alt CodeAlt 8734
HTML Code∞
HTML Entity∞
CSS Code\221E
Hex Code∞
UnicodeU+221E

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 8734. 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: &#8734;</b>My symbol: ∞

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

HTML TextOutput
<b>My symbol: &infin;</b>My symbol: ∞

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

CSS and HTML TextOutput
<style>
span:after {
content: "\221E";}
</style>
<span>My symbol:</span> 		My symbol: ∞

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

HTML TextOutput
<b>My symbol: &#x221E;</b>My symbol: ∞
On the assumption that you already have your canvas and the context set up, use the Hex code in the format 0x221E to place the ∞ symbol on your canvas. For example:
JavaScript Text
const x = "0x"+"E9"
ctx.fillText(String.fromCodePoint(x), 5, 5);
Output

∞

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

The Unicode for ∞ is U+221E. 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:
TypeOutput
221E
[Hold down Alt]
[Press x]		∞
(The 221E turns into ∞. Note that you can omit any leading zeros.)
In JavaScript, the syntax is \uXXXX. So, our example would be \u221E. (Note that the format is 4 hexadecimal characters.)
JavaScript TextOutput
let str = "\u221E"
document.write("My symbol: " + str)		My symbol: ∞