What ﹟ means
It carries #’s reading.
In a hashtag, it introduces the tag; elsewhere, # marks a number or means pound/hash.
Taiwan’s CNS 11643 character-set standard appeared in 1986; Unicode retains ﹟ for compatibility with older East Asian encodings.
Use # for new text
NFKC or NFKD text normalization changes ﹟ to #, erasing the small-form distinction. Fonts may also render it reduced inside a full-width East Asian character cell.
Don't confuse it with
2Questions people ask
1Why does ﹟ show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type ﹟
Windows (Word)
Alt+XType FE5F, 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 “small number sign”.
Linux
Ctrl+Shift+UType fe5f, then Enter or Space.
HTML
﹟CSS
\FE5FUnicode picker
Search “small number sign” in a Unicode-aware picker; the # key produces #, not ﹟.
Codes and encoding1 code points
HTML decimal
﹟
HTML hex
﹟
CSS content
content: "\FE5F";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%EF%B9%9F
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.