What 𝟝 means
It began as a blackboard shortcut. Mathematicians doubled strokes when bold chalk was unavailable. In 1895, Giuseppe Peano used N in print for whole numbers above zero; mathematical type later used blackboard-bold letters to distinguish named groups of numbers. 𝟝 applies that style to five. Fonts vary, but the doubled strokes remain part of the style.
Don't confuse it with
1Questions people ask
1Why did 𝟝 turn into 5?
It can happen. NFKC compatibility normalization can remove its mathematical styling and yield plain 5. If the distinction matters in a formula, avoid that conversion.
How to type 𝟝
Windows (Word)
Alt+XType 1D7DD, then Alt+X to get 𝟝.
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 five”.
Linux
Ctrl+Shift+UType 1d7dd, then Enter or Space.
HTML
𝟝CSS
\1D7DDCodes and encoding1 code points
HTML decimal
𝟝
HTML hex
𝟝
CSS content
content: "\1D7DD";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%F0%9D%9F%9D
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.