How do I produce Theorems and equations which are numbered by hand?

Question

I'd like to be able to write a LaTex document with numbered theorems and equations, but I would like not to have them numbered automatically, but rather put in by hand. Ideally, I'd like to be able to write something like

\begin{thm-handnumbered}{3.1416}.  
The number $\pi$ is rational.
\end{thm-handnumbered}

As a consequence,
\begin{equation-handnumbered}{2.718}
e^{\pi i} = -1.003+0.014 i.
\end{equation-handnumbered}

and so produce "Theorem 3.1416", and an equation numbered "(2.718)".

(I can create a new theorem type for each numbered theorem (\newtheorem{thm-3.1416}...), but I've got a lot of them. I can handcraft a "thm-handnumbered" command, but it looks ugly...)

Answer 1

And here's a solution for hand-numbered theorems.

\documentclass{article}

\usepackage{amsthm}
\usepackage{thmtools}
\declaretheoremstyle[notefont=\bfseries,notebraces={}{},%
    headpunct={},postheadspace=1em]{mystyle}
\declaretheorem[style=mystyle,numbered=no,name=Theorem]{thm-hand}

\begin{document}

\begin{thm-hand}[3.1416]
Some text.
\end{thm-hand}

\end{document}

Answer 2

For the second one, you could use \tag from the amsmath package:

\begin{equation}\tag{2.718}
e^{\pi i} = -1.003+0.014 i.
\end{equation}

For the first, I'd use ntheorem with a no-number style and then use the optional name:

\usepackage{ntheorem}
\theoremstyle{nonumberplain}
\newtheorem{handnum-theorem}{Theorem}

And in the body:

 \begin{handnum-theorem}[3.1416]
     This result is interesting.
 \end{handnum-theorem}

See the ntheorem documentation for more info.