HTML Entity for Double Struck Italic Capital D (ⅅ)

Beginner
⏱️ 5 min read
📚 Updated: Jun 2026
🎯 1 Code Example
Unicode U+2145
HTML entity for Double Struck Italic Capital D (U+2145) tutorial illustration

What You'll Learn

How to display the Double Struck Italic Capital D (ⅅ) in HTML using hexadecimal, decimal, the named entity ⅅ, and CSS escape methods. This character is U+2145 (DOUBLE-STRUCK ITALIC CAPITAL D) in the Letterlike Symbols block (U+2100–U+214F)—the double-struck italic form of Latin capital D used in mathematics and differential notation.

Render it with ⅅ, ⅅ, ⅅ, or CSS escape \2145. For the small variant use ⅆ (U+2146, ⅆ). See also math entities.

⚡ Quick Reference — Double Struck Italic Capital D

Unicode U+2145

Letterlike Symbols block

Hex Code ⅅ

Hexadecimal reference

HTML Code ⅅ

Decimal reference

Named Entity ⅅ

HTML5 named entity for U+2145

Reference Table
Name           Value
────────────   ──────────
Unicode        U+2145
Hex code       ⅅ
HTML code      ⅅ
Named entity   ⅅ
CSS code       \2145
Related        U+2146 = Small d (ⅆ)
1

Complete HTML Example

This example demonstrates the Double Struck Italic Capital D (ⅅ) using hexadecimal code, decimal HTML code, the named entity ⅅ, and a CSS content escape:

html
<!DOCTYPE html>
<html>
<head>
 <style>
  #point:after{
   content: "\2145";
  }
 </style>
</head>
<body>
<p>Double Struck Italic Capital D using Hexadecimal: &#x2145;</p>
<p>Double Struck Italic Capital D using HTML Code: &#8517;</p>
<p>Double Struck Italic Capital D using HTML Entity: &DD;</p>
<p id="point">Double Struck Italic Capital D using CSS Entity: </p>
</body>
</html>
Try it Yourself

🌐 Browser Support

U+2145 is widely supported in modern browsers when rendered with a font that includes Letterlike Symbols:

Chrome 1+
Firefox 1+
Safari 1+
Edge 12+
Opera 4+
Android 4.4+
iOS Safari 1+

👀 Live Preview

See the Double Struck Italic Capital D (ⅅ) in mathematical notation:

Large glyph ⅅ
Capital vs small ⅅ capital   ⅆ small
Named entity &DD; → ⅅ
All HTML refs &#x2145; &#8517; &DD;
CSS escape \2145

🧠 How It Works

1

Hexadecimal Code

&#x2145; uses the Unicode hexadecimal value 2145 to display the Double Struck Italic Capital D. The x prefix indicates hexadecimal format.

HTML markup
2

Decimal HTML Code

&#8517; uses the decimal Unicode value 8517 to display the same character.

HTML markup
3

Named HTML Entity

&DD; is the HTML5 named entity for U+2145. It is easy to read in source and resolves to the same character (ⅅ).

HTML markup
4

CSS Entity

\2145 is used in CSS stylesheets, particularly in the content property of pseudo-elements like ::before and ::after.

CSS stylesheet
=

Same visual result

All four methods produce: ⅅ. Unicode U+2145. Small variant: &dd; (ⅆ, U+2146).

✅

Use Cases

The Double Struck Italic Capital D (ⅅ) commonly appears in:

📐 Differential notation

Calculus and mathematics where the double-struck italic D denotes a derivative or differential operator.

🔬 Set theory & domains

Domain notation and set theory where this letterlike symbol distinguishes from the regular letter D.

📚 Academic publishing

Textbooks, papers, and course materials requiring letterlike math symbols in HTML.

💻 Math on the web

Equation editors and math rendering alongside other double-struck italic letters.

📖 Unicode references

Entity lists and guides for Letterlike Symbols (U+2100–U+214F).

♿ Accessibility

Use math-capable fonts so ⅅ renders clearly for all readers.

💡 Best Practices

Do

  • Use &DD; for readable markup, or &#x2145; / &#8517;
  • Use math fonts (Cambria Math, STIX Two Math) for reliable rendering
  • Distinguish ⅅ (capital) from ⅆ (&dd;, small)
  • Use \2145 only inside CSS content
  • Keep entity style consistent across the document

Don’t

  • Confuse &DD; (U+2145) with unrelated entities
  • Use &dd; when you need capital ⅅ
  • Put CSS escape \2145 in HTML text nodes
  • Forget UTF-8 (<meta charset="utf-8">) on math pages
  • Assume every font includes Letterlike Symbols

Key Takeaways

1

Named entity available: &DD;

&#x2145; &#8517;
2

For CSS stylesheets, use the escape in the content property

\2145
3

Unicode U+2145 DOUBLE-STRUCK ITALIC CAPITAL D

4

Small d: ⅆ via &dd; or &#x2146;

5

Four methods, one glyph — widely supported in modern browsers

❓ Frequently Asked Questions

Use &#x2145; (hex), &#8517; (decimal), &DD; (named entity), or \2145 in CSS content. All produce ⅅ.
U+2145 (DOUBLE-STRUCK ITALIC CAPITAL D). Letterlike Symbols block (U+2100–U+214F). Hex 2145, decimal 8517. Double-struck italic form of Latin capital D.
When you need the double-struck italic capital D in mathematical content: differential notation, set theory, domain notation, expressions, or academic papers requiring this letterlike symbol.
HTML references (&#8517;, &#x2145;, or &DD;) go in markup. The CSS escape \2145 is used in stylesheets, typically in the content property of pseudo-elements.
&DD; is easier to read in source than &#8517; or &#x2145;, but all produce ⅅ. The named entity is part of the HTML5 entity set for Letterlike Symbols.

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About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

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