Addition is Hard

Dang this problem is a tough one, at least if you are php.

The question hint has this: "0x0 +0x7068703f"

I forgot my ascii, so I had to python:

>>> '7068703f'.decode('hex')
'php?'

So let's copypaste that into php and see what happens:

$ cat t.php 
<?php
echo 0x0 +0x7068703f;
echo "\n";
?>

$ php5 t.php 
3771785342