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<html lang="en-US">
<head>
<style>
#point:after{
content:"\0004F";
}
</style>
</head>
<body>
<p>Uppercase O using Hexa Decimal: O</p>
<p>Uppercase O using HTML Code: O</p>
<p>Uppercase O using HTML Entity: O</p>
<p id="point">Uppercase O using CSS Entity: </p>
</body>
</html>