What ⨹ means
Do not read ⨹ as ordinary + by default. MathML, a format for web equations, uses triplus to name the glyph, not a calculation.
Technical notation; define it in context.
Don't confuse it with
3Questions people ask
1Can a font omit ⨹?
Yes. Without the glyph, a font may show a missing box or substitute another design. Use a math font with ⨹ for exact display.
How to type ⨹
Windows (Word)
Alt+XType 2A39, then Alt+X to get ⨹.
Windows
Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).
macOS
Control+Command+SpaceOpen the character viewer and search “plus sign in triangle”.
Linux
Ctrl+Shift+UType 2a39, then Enter or Space.
HTML
⨹CSS
\2A39MathML
Use `⨹` where supported; otherwise enter ⨹.
LaTeX
If your math-typesetting setup lacks a command, use a font with ⨹ or define it in your package.
Codes and encoding1 code points
HTML decimal
⨹
HTML hex
⨹
CSS content
content: "\2A39";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%A8%B9
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.