Decimal to Hexadecimal

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Decimal-to-Hexadecimal</title>
</head>
<body>
<script>
    var num = parseInt(prompt("Enter a positive integer number"));
    alert(num.toString(16).toUpperCase());
</script>
</body>
</html>