regular expression

i need to receive number 527 from regular expression :
my html code:
<span class="labelbitdetail green"><i class="icon-thumbs-up norightmargin"></i> 527</span>
i want to use php i think to use preg_match ()
can you help me to create php code?
i think
preg_match(<span class=\"labelbitdetail green\">(.*?)<\/span>< class=\"icon-thumbs-up norightmargin\">/",$content,$aPages);

 

Here you have it, https://regex101.com/r/kZ9qR2/1

Or, simply, in php:
http://runnable.com/VOQvyTPUXlBY5e_x/page-detect-regex-for-php

Regards.