<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
#point:after{
content:"\02205";
}
</style>
</head>
<body>
<p>Empty Set using Hexa Decimal: ∅</p>
<p>Empty Set using HTML Code: ∅</p>
<p>Empty Set using HTML Entity: ∅</p>
<p id="point">Empty Set using CSS Entity: </p>
</body>
</html>