How do I make theorems and equations share numbering? The default numbering system goes like this:
Theorem 1. Blah blah blah...
1=0+1 (1)
Theorem 2. More blahs...
Theorem 3. No more blahs...
2=1+1 (2)
The numbers in the parenthesis are equation numbers. How do you change the above into this:
Theorem 1. Blah blah blah...
1=0+1 (2)
Theorem 3. More blahs...
Theorem 4. No more blahs...
2=1+1 (5)
I am using ntheorem package, but couldn't figure out how. Would I need to use a different package?
You just need to tell it to number your theorems using the equation counter.
\newtheorem{thm}[equation]{Theorem}
Now \begin{thm} will be numbered the same as \begin{equation}.
See the amsthm documentation. It is only a few pages long and includes a discussion of this point (as well as lots of others relating to theorem styles).
Here's a solution using the thmtools package in addition to ntheorem.
\documentclass{article}
\usepackage{ntheorem}
\usepackage{thmtools}
\declaretheorem[numberlike=equation]{theorem}
\begin{document}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\begin{theorem}
Some text.
\end{theorem}
\end{document}
