<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
#point:after{
content:"\0222C";
}
</style>
</head>
<body>
<p>Double Integral using Hexa Decimal: ∬</p>
<p>Double Integral using HTML Code: ∬</p>
<p>Double Integral using HTML Entity: ∬</p>
<p id="point">Double Integral using CSS Entity: </p> </body>
</html>