∛
∛ Cube Root Symbol
The cube root symbol (∛) is a radical with a small 3 — the number that gives x when multiplied by itself three times.
Also known as: cube root symbol, cubic root symbol, third root, radical 3.
Codes
| Symbol | ∛ | |
| Square root | √ · U+221A | |
| Unicode | U+221B | |
| HTML entity (decimal) | ∛ | |
| HTML entity (hex) | ∛ | |
| CSS | \221B | |
| LaTeX | \sqrt[3]{x} | |
| Windows Alt code | Alt + 8731 |
How to type ∛ (Cube Root Symbol)
Windows221B, Alt + X
In Word, type 221B then press Alt + X. Elsewhere, copy ∛ above or use Character Map (search “cube root”).
Mac
No default keystroke. Open Character Viewer (Control + Cmd + Space) and search “cube root”, or copy ∛ above.
Microsoft Word221B, Alt + X
Type 221B, then press Alt + X to convert it to ∛.
Google Docs
Insert → Special characters, then search “cube root”. In an equation, \sqrt then the radical tool lets you set the index to 3.
LaTeX\sqrt[3]{x}
Use \sqrt[3]{x} in math mode — the optional argument is the index. \sqrt[n]{x} generalises it.
Usage
- ∛8 = 2, because 2 × 2 × 2 = 8. Unlike a square root, a cube root is defined for negative numbers: ∛(−8) = −2.
- The character ∛ carries its own index, so you cannot change it — for an nth root you need a real radical (LaTeX \sqrt[n]{x}) rather than a Unicode character. Unicode stops at ∜ (U+221C, fourth root).
- Like √ (U+221A), the character ∛ is only the radical sign. It does not draw the overbar (the vinculum) across the number, so ∛8 relies on the reader to see where the radicand ends. In typeset math, use a proper radical.
- The exponent form is often easier in code and in spreadsheets: ∛x is the same as x^(1/3).