Invalid escape sequence with my Regex
<p>I keep getting invalid escape sequence with my Regex</p>

<pre><code>private String mathA = "(\d)[ + ](\d)\\s=\?";
</code></pre>

<p>I erased every part of the Regex but no matter what I took out it kept giving me the same error. I want to match "5 + 3 =?" where the 5 and 3 can be any digit.</p>