$n = 6;
$arr = array(200, 3, 4, 5, 7, 10, 9);
$filtered_elements = array_filter($arr, function($element) use($n){return $element < $n;});
echo "Elements < $n:<br />";
print_r($filtered_elements);
/*
run:
Elements < 6:
Array ( [1] => 3 [2] => 4 [3] => 5 )
*/