PHP - If number is divisible by 3 and 5 then echo

$num_count = 100;
    $div_3 = "Divisible by 3";
    $div_5 = "Divisible by 5";
    $div_both = "Divisible by 3 and 5";
    $not_div = "Not Divisible by 3 or 5";

    for($i=0;$i<=$num_count;$i++)
    {
        switch($i)
        {
            case ($i%15==0):
            echo $i." (".$div_both.")</br>";
            break;
            case ($i%3==0):
            echo $i." (".$div_3.")</br>";
            break;
            case ($i%5==0):
            echo $i." (".$div_5.")</br>";
            break;
            default:
            echo $i."</br>";
            break;
        }
    }

if I'm reading your question correct then you are looking for :

if ($number % 3 == 0 && $number %5 == 0) {
        echo "BY3 AND 5";
} elseif ($number % 3 == 0)  {
    echo "BY3";
} elseif ($number % 5 == 0) {
    echo "BY5";
}

Alternative version :

echo ($number % 3 ? ($number % 5 ? "BY3 and 5" : "BY 3") : ($number % 5 ? "BY 5" : ""));

Nope... you should check first if it's divisble for 15 (3x5) (or 3 and 5) and after you can do other checks:

if($number % 15 == 0)  {
    echo "BY3 AND 5";
} elseif ($number % 5 == 0) {
    echo "BY5";
} elseif ($number % 3 == 0) {
    echo "BY3";
}
 echo "</td></tr>";

?>

Because every number divisble for 15 is also divisble for 3 and 5. So your last check could never hit