Question: How to set the column width in the align environment.
I've got a align environment to demonstrate how to do division by hand so the columns always contain only one number, but the columns are much wider than this.

Following an example only showing the ugly result because of to wide columns:

```
\begin{align}
    &1&2&3&4&4\\
    & & & &2&4\\
\end{align}

```

Answer: 
Note: This is based very heavily on Stefan Kottwitz's answer; I've just used some macros to make it a little bit more flexible.

```
\documentclass{article}
\usepackage{mathtools}

\newcommand{\leftsidelength}{}
\newcommand{\leftside}[1]{\hphantom{\leftsidelength}\mathllap{#1}}

\begin{document}

\begin{enumerate}
\renewcommand{\leftsidelength}{1+1}
\item $\leftside{\leftsidelength} = 2$ 
\item $\leftside{1} = 2 - 1$
\end{enumerate}

\end{document}

```

Someone who knows what they're talking about may tell me that there's a much better way to do this, but it seems to work. More importantly, if there is more than one line, it eliminates typing redundancy for the "phantomized" longest line, which makes for a more robust setup. 

The only missing component would be an automatic way to determine which left side is longest.
I tried once (and was surprised that it actually work) to use `\item` inside `\intertext` of the nested `align` environment:

```
\begin{enumerate}
     \item First point, blah
     \begin{align}
          a &= b+2  \\ %% not sure about whether those \\ are needed or not
      \intertext{\item Second point, blah}
          b &= c+3
     \end{align}
\end{enumerate}

```