What 𝟛 means
Its numeric value is three. Its role comes from the surrounding formula.
Double strokes began as a chalkboard workaround
Writers doubled strokes on blackboards to distinguish bold math without bold chalk. The hand-drawn convention later became a typeface; Unicode's model forms echo those board shapes.
Don't confuse it with
1Questions people ask
2Does text normalization turn 𝟛 into 3?
Yes. Unicode's NFKC compatibility normalization maps it to plain 3. The value stays three, but its double-struck distinction disappears.
Why does 𝟛 show as a box?
The active font lacks this glyph. A font with support is needed to draw its intended double-struck shape.
How to type 𝟛
Windows (Word)
Alt+XType 1D7DB, then Alt+X to get 𝟛.
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 “mathematical double-struck digit three”.
Linux
Ctrl+Shift+UType 1d7db, then Enter or Space.
HTML
𝟛CSS
\1D7DBCodes and encoding1 code points
HTML decimal
𝟛
HTML hex
𝟛
CSS content
content: "\1D7DB";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%F0%9D%9F%9B
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.