How to type ⅀ on Windows
The fastest method on a full-size keyboard is the Alt code Alt+8512.
- Make sure Num Lock is on.
- Hold down the Alt key.
- Type 8512 on the numeric keypad (the number row will not work).
- Release Alt. The double-struck n-ary summation symbol ⅀ appears.
Note: Alt+8512 is a Unicode decimal code, not a classic code-page Alt code. It works in Microsoft Word, WordPad and some other apps, but not in Notepad or most browsers. In those apps, copy the symbol from this page instead.
No numeric keypad?
Press Win+. to open the emoji panel, choose the Symbols tab (Ω) and search for "double-struck n-ary summation". Or open Character Map from the Start menu, find ⅀, click Select, then Copy.
How to type ⅀ on a Mac
There is no direct keyboard shortcut for ⅀ on a Mac.
For any symbol, the Character Viewer works: press Control+⌘+Space, type "double-struck n-ary summation" in the search box and double-click the result. It will be remembered under Frequently Used.
How to type ⅀ on iPhone and iPad
The iOS keyboard does not include ⅀, so the reliable way is to copy it from this page, then press and hold in any text field and tap Paste.
If you use it often, create a shortcut: open Settings → General → Keyboard → Text Replacement, paste ⅀ in the Phrase field and type a short code such as ;double in the Shortcut field. Typing that code will then insert ⅀ anywhere.
How to type ⅀ on Android
Copy the symbol from this page, then long-press in a text field and choose Paste. Gboard also keeps a clipboard history: tap the clipboard icon on the toolbar to paste it again later.
For a permanent shortcut, open Gboard settings → Dictionary → Personal dictionary, add ⅀ as the word and a short code as the shortcut.
How to type ⅀ in Microsoft Word
- Type the Unicode hex code 2140 where you want the symbol.
- Press Alt+X. Word converts the code into ⅀.
This works on Windows in Word, Outlook and OneNote and needs no numeric keypad. You can also go to Insert → Symbol → More Symbols, set the font to a Unicode font and type 2140 in the Character code box. In Excel, the formula =UNICHAR(8512) returns the symbol.
How to type ⅀ in Google Docs
Open Insert → Special characters, then either search for "double-struck n-ary summation" or draw the symbol in the sketch box. Click the result to insert it. In Google Sheets, use =CHAR(8512).
⅀ in HTML, CSS and code
| Format | Code |
|---|---|
| HTML entity | ⅀ |
| HTML decimal | ⅀ |
| HTML hex | ⅀ |
CSS content | "\2140" |
| JavaScript | "\u2140" |
| Python | "\u2140" |
| URL encoded | %E2%85%80 |
Because ⅀ is a standard Unicode character (U+2140), you can also paste it directly into any UTF-8 file. The escaped forms above are only needed when the file encoding is uncertain or the symbol must be entered on a keyboard without it.
Where the double-struck n-ary summation symbol is used
This symbol appears mainly in advanced mathematical texts and Unicode math font sets, where blackboard bold style distinguishes it from the standard summation sign ∑. Example: "⅀ₙ aₙ" in a paper using double-struck notation. It is not commonly used in everyday writing.
Frequently asked questions
What does ⅀ mean compared to ∑? +
They represent the same summation operation, but ⅀ uses double-struck (blackboard bold) styling, often to distinguish a special context or notational convention from the regular ∑ symbol.
Is ⅀ used in standard math classes? +
No, it's rare outside specialized texts or documents that use full blackboard bold alphabets and operators for stylistic or notational consistency.
What is the Alt code for the double-struck n-ary summation symbol? +
The Alt code for ⅀ is Alt+8512. Hold Alt, type 8512 on the numeric keypad, then release Alt. This is a Unicode code, so it works in Word and WordPad but not in every app; in other apps paste the symbol instead.
How do I type ⅀ on a Mac? +
There is no dedicated Mac shortcut for ⅀. Open the Character Viewer with Control + Command + Space, search for "double-struck n-ary summation", and double-click it. Or copy it from this page.
How do I type the double-struck n-ary summation symbol on iPhone or Android? +
Phone keyboards do not include ⅀ by default. Copy it from this page and paste it, or add it as a text replacement shortcut in Settings so you can type it with a short abbreviation.
What is the HTML code for ⅀? +
Use ⅀ in HTML. In CSS use content: "\2140" and in JavaScript use "\u2140".