Calculate Alexa Rank

So simple, Here 322623 is alexa rank

<?php
//my site rank 322623
echo round(pow(322623,-1.008)*104943144672); // monthly visitor
echo "<hr />";
echo ceil(round(pow(322623,-1.008)*104943144672)/30); // daily visitor
?>

Output:
293893 //monthly
9797 //daily

Source:
http://stackoverflow.com/questions/18444030/alexa-rank-to-traffic-estimation-formula