<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Függvények</title>
</head>
<body>
    <form action="" method="POST">
        <input type="number" name="num1"> + 
        <input type="number" name="num2">
        <button type="submit">Összead</button>
    </form>
    <p><?php echo $value?></p>
</body>
</html>