echo'<form name="form" action="" method="POST">

        Birinchi sonni kiriting:<br>

        <input type="number" name="son1" required><br>

        Ikkinchi sonni kiriting:<br>

        <input type="number" name="son2" required><br>

        <input name="yech" type="submit" value="Yechimni ko\'rish">

    </form>';