How to multiply select box option and a field dynamically in php
<p>I have a select box like</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;select name="abc"&gt;
  &lt;option&gt; 0 &lt;/option&gt;
  &lt;option&gt; 1 &lt;/option&gt;
  &lt;option&gt; 2 &lt;/option&gt;
  &lt;option&gt; 3 &lt;/option&gt;
&lt;/select&gt;</code></pre>
</div>
</div>
</p>

<p>and a normal text value like 1000.
i want to multiply 1000 with the option being selected in the text box dynamically without form and submit button.
How would i be able to do that.</p>

<p>Please Help.</p>

<p>Thanks</p>