What 𝍶 means
The practice is called 正の字 (sei-no-ji) in Japanese and 正字 (zhèng zì) in Chinese. A 2016 Unicode proposal also documents examples in Japanese public material and a Korean counting lesson.
Don't confuse it with
1Combination ideas
2Six: one complete group plus one stroke.
Ten: two complete five-count groups.
Questions people ask
1Why does 𝍶 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 𝍶
Windows (Word)
Alt+XType 1D376, then Alt+X to get 𝍶.
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 “ideographic tally mark five”.
Linux
Ctrl+Shift+UType 1d376, then Enter or Space.
HTML
𝍶CSS
\1D376Codes and encoding1 code points
HTML decimal
𝍶
HTML hex
𝍶
CSS content
content: "\1D376";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%F0%9D%8D%B6
1
On screen
1
Code points
2
JS .length
4
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.