The basic math signs
To type a sign in Microsoft Word, type its code point digits (for example 00D7) and then press Alt+X; Word converts the code into the character. In HTML, use the named reference or the numeric form ×.
| Sign | Unicode name | Code point | HTML | Word (type, then Alt+X) | Notes |
|---|---|---|---|---|---|
| + | PLUS SIGN | U+002B | + | 002B | Addition; also marks a positive number. |
| − | MINUS SIGN | U+2212 | − | 2212 | Subtraction and negative numbers. Keyboards type the shorter hyphen-minus (-, U+002D) instead. |
| - | HYPHEN-MINUS | U+002D | — | 002D | The keyboard hyphen, used as a minus sign in plain text and programming. |
| × | MULTIPLICATION SIGN | U+00D7 | × | 00D7 | The times sign. In algebra a middle dot or juxtaposition (3x) is common; programming uses *. |
| ÷ | DIVISION SIGN | U+00F7 | ÷ | 00F7 | The obelus. Many countries and most advanced texts write a/b or a fraction instead. |
| = | EQUALS SIGN | U+003D | = | 003D | Both sides have the same value. |
| ≠ | NOT EQUAL TO | U+2260 | ≠ | 2260 | The two sides differ. |
| ± | PLUS-MINUS SIGN | U+00B1 | ± | 00B1 | Both the sum and the difference, as in the quadratic formula; also a tolerance, 5 ± 0.1 mm. |
| ∞ | INFINITY | U+221E | ∞ | 221E | Unboundedness; see below. |
Sources: Unicode Consortium: Unicode chart: C0 Controls and Basic Latin (U+0000–U+007F); Unicode Consortium: Unicode chart: Latin-1 Supplement (U+0080–U+00FF); Unicode Consortium: Unicode chart: Mathematical Operators (U+2200–U+22FF); WHATWG: HTML Standard: Named character references; Microsoft Support: Insert ASCII or Unicode Latin-based symbols and characters
The infinity symbol ∞
∞ is U+221E INFINITY in the Mathematical Operators block. Its HTML named reference is ∞ and its numeric reference is ∞ (or ∞).
- Microsoft Word on Windows: type 221E, then press Alt+X
- Mac: press Fn/Globe-E or choose Edit > Emoji & Symbols to open the Character Viewer, search for “infinity” and click ∞
- Facebook, messaging apps and other websites: there is no site-specific shortcut; insert ∞ with your system's character picker (above) or copy and paste it from this page
- HTML and web pages: ∞
- Keyboard: standard keyboard layouts have no dedicated ∞ key; the methods above work in most apps
Sources: Microsoft Support: Insert ASCII or Unicode Latin-based symbols and characters; Apple Support: Use emoji and symbols on Mac; WHATWG: HTML Standard: Named character references
Is infinity a number?
Infinity is not a real number: no real number is larger than every other, and ∞ does not obey ordinary arithmetic (∞ − ∞ and ∞ ÷ ∞ have no single value). In calculus ∞ is shorthand for “grows without bound,” as in lim x→∞ 1/x = 0.
Some number systems do include infinite elements. The extended real line adds +∞ and −∞ with rules such as x + ∞ = ∞, set theory measures infinite sets with cardinal numbers (the integers and the reals are different sizes of infinity), and computer floating-point arithmetic (IEEE 754) has explicit +Infinity and −Infinity values.