[Tex/LaTex] How to write upside down real numbers symbol ($\mathbb{R}$)

Question

How can I write $\mathbb{R}$ upside down? And, in general, \mathbb letters…

Answer 1

1. \umathbb{R} for u​pside down
2. \rmathbb{R} for r​eflected
3. \fmathbb{R} for f​lipped

\documentclass{article}

\usepackage{amsfonts}
\usepackage{graphicx}

\makeatletter
\newcommand{\umathbb}[1]{{\mathpalette\dude@umathbb{#1}}}
\newcommand{\dude@umathbb}[2]{%
  \raisebox{\depth}{\rotatebox{180}{$\m@th#1\mathbb{#2}$}}%
}
\newcommand{\rmathbb}[1]{{\mathpalette\dude@rmathbb{#1}}}
\newcommand{\dude@rmathbb}[2]{%
  \scalebox{-1}[1]{$\m@th#1\mathbb{#2}$}%
}
\newcommand{\fmathbb}[1]{{\mathpalette\dude@fmathbb{#1}}}
\newcommand{\dude@fmathbb}[2]{%
  \raisebox{\depth}{\scalebox{1}[-1]{$\m@th#1\mathbb{#2}$}}%
}
\makeatother

\begin{document}

$A\umathbb{R}B$ $A\rmathbb{R}B$ $A\fmathbb{R}B$

$X_{\umathbb{R}}$ $X_{\rmathbb{R}}$ $X_{\fmathbb{R}}$

\end{document}