For this, you can simply use for loop.
Example
The PHP code is as follows
<!DOCTYPE html>
<html>
<body>
<?php
$list="10 20 30 40 50 60";
$arr=[];
$counter=0;
for($i=0;$i<count($list);$i++){
if($list!==" "){
$arr[$counter++]=$list;
}
}
foreach($arr as $t){
echo $t,"<br>";
}
?>
</body>
</html>Output
This will produce the following output
10 20 30 40 50 60