Something

<?php
        $myList =  array(1,2,3,4,5);
 	$myM = 10;

        function mult($list, $m) {
                $list = array_values($list);
                for ($i = 0; $i < count($list); ++$i) {
                         $list[$i] *= $m;
                }
                return $list;
        }
 
        $myList = mult($myList, $myM);
    
        echo implode(",",$myList);
?>