## LaTeX forum ⇒ Fonts & Character Sets ⇒ Blackboard bold numbers; trouble with \mathbb

Information and discussion about fonts and character sets (e.g. how to use language specific characters)
299792458
Posts: 2
Joined: Thu Jan 19, 2012 11:55 pm

### Blackboard bold numbers; trouble with \mathbb

Hello everyone,

I just started using LaTeX and I have an issue with the \mathbb command. Letters work just fine, but when I am trying to use double-struck numbers, e.g. with \mathbb{1}, this character

character.jpg (631 Bytes) Viewed 17898 times

shows up instead of the blackboard bold number 1. I did find out I can circumvent this by creating combining the characters "1" and "I" to make somewhat of a double-struck "1", but I would still like to know what is going wrong when I use \mathbb.

Any help would be appreciated.
Last edited by Stefan Kottwitz on Fri Jan 20, 2012 12:58 am, edited 1 time in total.

Stefan Kottwitz
Posts: 9415
Joined: Mon Mar 10, 2008 9:44 pm
Welcome to the board!

\mathbb (of amsfonts) supports only letters, not digits. You could use bbm:

\documentclass{article}\usepackage{bbm}\begin{document}$\mathbbm{1}$\end{document}

identity-bbm.png (433 Bytes) Viewed 17898 times

Or dsfont:

\documentclass{article}\usepackage{dsfont}\begin{document}$\mathds{1}$\end{document}

identity-ds.png (876 Bytes) Viewed 17898 times

Stefan

299792458
Posts: 2
Joined: Thu Jan 19, 2012 11:55 pm
Thanks for the quick response.

I have a follow-up beginner's question right away: Is there an easier way of installing dsfont in MiKTeX than figuring out by myself where to put the individual files, as the documentation suggests? As it appears to me the dsfont package cannot be installed via the package manager in MiKTeX.

localghost
Site Moderator
Posts: 9204
Joined: Fri Feb 02, 2007 12:06 pm
299792458 wrote:[…] I have a follow-up beginner's question right away: Is there an easier way of installing dsfont in MiKTeX than figuring out by myself where to put the individual files, as the documentation suggests? As it appears to me the dsfont package cannot be installed via the package manager in MiKTeX.

Search the package list in the MiKTeX Package Manager (MPM) for the doublestroke package and install it.

Thorsten
LaTeX Community Moderator

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