Untitled

!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
</head>
<body>
<form>
    Please Total Additional Units: <input type="text" name="num1"/>
    <input type="submit"/>
</form>
<?php
if (isset($_GET['num1'])) {
    $num1 = intval($_GET['num1']);

    echo "Total Cost in Rials = ";
    echo ($num1 * 50)+150;//calculating based on additional blocks. considering 1 block cost as 50 rials
}

?>
</body>
</html>