[Tex/LaTex] aligned environment, align numbers to right

Question

I have an "equation", where I simply want to give some constant values. I'm aligning on the equation symbols, but as the numbers have different amounts of digits, I would also like to align the numbers to the right:

LaTeX currently looks as follows:

\documentclass[ngerman]{scrbook}
\usepackage{amssymb,amsmath,amsthm}
\begin{document}
\begin{equation*}
    \begin{aligned}
    \text{first value} &= 12 & \\
    \text{second value} &= 1234 & \\
    \text{third one} &= 1234567 &
    \end{aligned}
\end{equation*}
\end{document}

Is it possible to align to the right with aligned? Are there any other packages for achieving this (I would like to stick to the equation if possible, for consistency reasons).

Answer 1

Like this?

\documentclass{scrbook}
\usepackage{amssymb,amsmath,amsthm}
\begin{document}
\begin{equation*}
    \begin{alignedat}{2}
    \text{first value} &={}& 12  \\
    \text{second value} &={}& 1234  \\
    \text{third one} &={}& 1234567
    \end{alignedat}
\end{equation*}
\end{document}

I have just moved the & before the numbers and used alignedat (thanks to egreg).

This is with \makebox:

\documentclass{scrbook}
\usepackage{mathtools}
\newcommand\mybox[1]{\makebox[1.5cm][r]{$#1$}}  %% change 1.5cm to fit in the largest integer
\begin{document}
\begin{equation*}
    \begin{aligned}
    \text{first value} &= \mybox{12}  \\
    \text{second value} &= \mybox{1234}  \\
    \text{third one} &= \mybox{1234567}
    \end{aligned}
\end{equation*}
\end{document}

Another option with a tabular:

\documentclass{scrbook}
\usepackage{amsmath,array}
\begin{document}
\begin{equation*}      %% or \begin{center}
    \begin{tabular}{r!{$=$}r}
    first value & 12  \\
    second value & 1234  \\
    third one & 1234567 
    \end{tabular}      %% or \end{center}
\end{equation*}
\end{document}

Here you can use begin{center} or \centering (within a group) instead of \begin{equation*}.