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HTML Entity Detail
HTML Entity - Not An Element Of
Not An Element Of is a mathematical operators, comparison symbols, and notation characters. This HTML entity enables web developers to display this character reliably across all browsers without encoding issues.
Symbol preview
∉
Unicode
U+2209
HTML entity
∉
CSS code
\2209
Usage Examples
Use this HTML entity in mathematical expressions and equations. For example, ≠ for not equal, ≤ for less than or equal, ∞ for infinity.
Related Entities
Common Mistakes
⚠️
Mistake: Using programming operators instead of proper math symbols
Fix: In mathematical content, use ≠ (≠) not !=, ≤ (≤) not <=, × (×) not x or *. Programming operators are meant for code, not mathematical notation.
⚠️
Mistake: Confusing similar math symbols with different meanings
Fix: Use ≅ (≅) for congruence, ≈ (≈) for approximate equality, ∼ (∼) for similarity. Each symbol has a distinct mathematical meaning.
Not An Element Of
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Category: Math Symbol
| Unicode | U+2209 |
|---|---|
| Hex Code | ∉ |
| HTML Code | ∉ |
| HTML Entity | ∉ |
| CSS Code | \2209 |
| Windows Shortcut | |
| Mac Shortcut | |
HTML code example
CSS code example
Last updated: 21 Jun 2026
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