Inline math goes between $ characters, and display math
goes between $$:
Let $x$ and $y$ be integers such that
$$x=y + 2$$
.
<p>Let <span class="math inline">\(x\)</span> and <span class="math inline">\(y\)</span> be integers such that
<span class="math display">\[x=y + 2\]</span></p>
In inline math, the opening $ must not be followed by
a whitespace, and the closing $ must not be
preceeded by whitespace.
This is not math: 2000$.
And neither is this $ 4 $.
Or this $4
$.
.
<p>This is not math: 2000$.
And neither is this $ 4 $.
Or this $4
$.</p>
Display math delimiters can be surrounded by whitespace:
This is display math:
$$
e=mc^2
$$
.
<p>This is display math:
<span class="math display">\[
e=mc^2
\]</span></p>
Note that math can contain embedded math. In scanning for a closing delimiter, we skip material in balanced curly braces:
This is display math:
$$
\text{Hello $x^2$}
$$
And this is inline math:
$\text{Hello $x$ there!}$
.
<p>This is display math:
<span class="math display">\[
\text{Hello $x^2$}
\]</span>
And this is inline math:
<span class="math inline">\(\text{Hello $x$ there!}\)</span></p>
To avoid treating currency signs as math delimiters, one may occasionally have to backslash-escape them:
The cost is between \$10 and 30$.
.
<p>The cost is between $10 and 30$.</p>
Dollar signs must also be backslash-escaped if they occur within math:
$\text{\$}$
.
<p><span class="math inline">\(\text{\$}\)</span></p>
Everthing inside the math construction is treated as math, and not given its normal commonmark meaning.
$b<a>c$
.
<p><span class="math inline">\(b<a>c\)</span></p>