The Mathematical Symbol "Plus minus symbol (±)"

The "Plus Minus" Symbol (±): Indicating Tolerance in Mathematics and Science

The lexicon of mathematical and scientific symbols is vast and varied, each with its distinct implications. Among them, the ± symbol, colloquially known as "Plus Minus", holds an important position. This symbol elegantly communicates the idea of variability, uncertainty, or tolerance around a value. Let's explore the ± symbol in more detail.

Unpacking the ± Symbol

The ± symbol is a compact way of representing both positive and negative deviations or directions from a given value. This is particularly useful in contexts where precision is paramount, but a value has inherent uncertainty or variability.

Example 1: Measurements in Physics

Consider the measurement of the speed of light as \( 299,792,458 \) meters per second. Due to measurement uncertainties, it might be presented as \( 299,792,458 ± 1 \) m/s, indicating a potential variation of 1 meter per second either way.

Example 2: Mathematics

In the solution of quadratic equations, the square root component can often have both positive and negative values, leading to two potential solutions. Representing this dual possibility compactly, the ± symbol is used.

Key Applications

The ± symbol finds its utility across multiple domains:

  • Physics and Engineering: Signifying measurement uncertainties or tolerances.
  • Mathematics: Denoting dual possibilities, especially in equations with multiple potential solutions.
  • Statistics: Indicating confidence intervals or margins of error.

Its ability to concisely communicate variability is invaluable in these disciplines, ensuring clarity without verbosity.

To wrap up, the ± symbol serves as a powerful tool in the world of mathematics and science, encapsulating the concept of variability around a central value. Its ubiquitous presence ensures that ideas of uncertainty, tolerance, or dual possibilities are easily and universally understood.

Mathematical symbol 'Plus minus symbol'

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Codes for the ± Symbol

The Symbol±
Alt CodeAlt 0177
HTML Code±
HTML Entity±
CSS Code\00B1
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 0177. 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: &#177;</b>My symbol: ±

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

HTML TextOutput
<b>My symbol: &plusmn;</b>My symbol: ±

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

CSS and HTML TextOutput
span:after {
content: "\00B1";}
<span>My symbol:</span>
My symbol: ±

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

HTML TextOutput
<b>My symbol: &#x00B1;</b>My symbol: ±
On the assumption that you already have your canvas and the context set up, use the Hex code in the format 0x00B1 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+00B1. 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 00B1 turns into ±. Note that you can omit any leading zeros.)
In JavaScript, the syntax is \uXXXX. So, our example would be \u00B1. (Note that the format is 4 hexadecimal characters.)
JavaScript TextOutput
let str = "\u00B1"
document.write("My symbol: " + str)
My symbol: ±