How do I pass numeric arguments to Latex environments

Question

I have defined an environment as

\newenvironment{question}[1]
{Question (#1 points):}{}

I am using it as

\begin{question}[10]
...
\end{question}

I get the following error:

Missing number, treated as zero
\begin{question}[
                 10]

Answer 1

The proper syntax is with a curly brace, not a square brace:

\begin{question}{10}
What is the airspeed velocity of an unladen swallow?
\end{question}