Remove everything from a string but numbers, dots and single letters with preg_replace
<p>How to modify this code to remove <strong>everything from a given string exept</strong> <em>numbers</em> (already there) <strong>AND</strong> <em>strings</em>: ".", "k ", "B ", and "M "?</p>

<p>What Im doing is parsing prices given in: 123k, 124.7B, 20M</p>

<pre><code>preg_replace("/\D/", "", "&lt;td&gt;Cost: 20b $, Sell for: 139k $&lt;/td&gt;" );
</code></pre>
