<form action="" method="post">
<input type="text" name="dolar" /><br />
<input type="submit" name="submit" value="Submit" />
</form>
<?php
if($_POST['submit']) {
(int) $var = $_POST['dolar'];
$var2 = $var/100;
echo number_format($var2, 2, ".", ",").' $';
}
?>