Alignment and phantom

Question

The MWE shows in the result the alignment as I need it in the first step. My questions are:

1. Now after the "1" there should appear again a "4", exactly beneath the "4" of the very first line. How can I do this?

2. Is there a more elegant solution in general (so that question 1 can be solved more easily)?

   \documentclass{article}
   \usepackage{amsmath}
    \begin{document}
    \begin{equation*}
    \begin{aligned}
     &&\sqrt{05\;47\;56} = 2 \\
     &-&4\phantom{\sqrt{05\;47\;56}} \\
     &&\rule{1cm}{0.4pt} \phantom{\sqrt{05\;47}} \\
    &&1\phantom{\sqrt{05\;47\;56}}
    \end{aligned}
    \end{equation*}
    \end{document}
   

Answer 1

You can use \mathmakebox and array. In the first column, the radical is placed as if it had the width of the radical sign (and no vinculum).

\documentclass{article}
\usepackage{amsmath,mathtools,calc}

\begin{document}

\begin{equation*}
\setlength{\arraycolsep}{0pt}
\begin{array}{r r @{\;} r @{\;} r c l}
\mathmakebox[\widthof{$\sqrt{\vphantom{0}}$}][l]{\sqrt{\phantom{05\;47\;56}}} &
    05 & 47 & 56 & {}={} & 2 \\
-&   4 \\
\cline{2-2}
 &   1
\end{array}
\end{equation*}

\end{document}

The complete scheme:

\documentclass{article}
\usepackage{amsmath,mathtools,calc}

\begin{document}

\begin{equation*}
\setlength{\arraycolsep}{0pt}
\begin{array}{r r @{\;} r @{\;} r c l}
\mathmakebox[\widthof{$\sqrt{\vphantom{0}}$}][l]{\sqrt{\phantom{05\;47\;56}}} &
    05 & 47 & 56 & {}={} & 234 \\
\cline{6-6}
-&   4 &    &    &       & 43\cdot3=129 \\
\cline{2-2} \cline{6-6}
 &   1 & 47 &    &       & 464\cdot4=1856 \\
-&   1 & 29 \\
\cline{2-3}
 &     & 18 & 56 \\
-&     & 18 & 56 \\
\cline{2-4}
 &     &    &  0
\end{array}
\end{equation*}

\end{document}

Answer 2

How about this code?

\documentclass{article}
\usepackage{mathtools}

 \begin{document}

 \begin{align*}
 \sqrt{05\;47\;56} & = 2 \\
  -\enspace 4\phantom{\;47\;56} & \\[-3ex]
\rule{1.1cm}{0.4pt} \phantom{\;56} & \\[-1.5ex]
 1\mathrlap{\;4}\phantom{\;47\;56} &
 \end{align*}

 \end{document}