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

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...)

• Why would you want to do this? Sep 6 '10 at 9:44
• It's useful for refereeing papers, where one wants to quote a few equations with the original numbering. Sep 7 '10 at 7:57
• It's also useful for students like me. I use a theorem environment for typing up exercises in my homework, and so I need the flexibility to manually fill in the appropriate exercise numbers.
– bcat
May 11 '11 at 2:53

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

\documentclass{article}

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

\begin{document}

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

\end{document}
• Looks good, thank you! (Took a few minutes to get thmtools installed correctly ... after you run "latex thmtools.ins", you need copy all the *.sty files into the texmf tree, not just the ones it tells you to copy ...) Sep 5 '10 at 20:54
• Thanks for accepting my answer - but don't forget that frabjous provided the solution for equations. (There's this button for useful answers.) Sep 5 '10 at 21:03
• I don't see a useful answer button ... or do you mean upvoting? (I don't have rep to do that yet.) Sep 5 '10 at 21:15
• Yes, I meant upvoting. I forgot its reputation requirement. Sep 5 '10 at 21:22
• This doesn't allow having a note after the theorem number as usual, right?
– Bach
Dec 12 '19 at 6:13

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}