<form action="">
    <input type="number" name="number1"/>
    <input type="number" name="number2"/>
    <input type="number" name="number3"/>
    <input type="submit" name="Bangladesh"/>
</form>
<?php
    if(isset($_GET['Bangladesh'])){
        $number1=$_GET['number1'];
        $number2=$_GET['number2'];
        $number3=$_GET['number3'];
        $numbers = array($number1,$number2,$number3);

        sort($numbers);

        $arrlength = count($numbers);

        for($x = 0; $x < $arrlength; $x++) {
            echo $numbers[$x];


            echo "<br>";
    }
    }
?>