Generate random number in Laravel Title Tag

Generate Title tag to change secrate code in Laravel and PHP 

Satrt *

1). Portable Storage Units 

Show data : PSU1482

$xx = '' ;

$pop  = rand(110,63654);

$string = rand(10,1000);

$bc = "+=";

$string = 'Portable Storage Units ' .$string;

//

// random_int(100000, 999999);

function initials($str) {

    $ret = '';

    foreach (explode(' ', $str) as $word)

        $ret .= strtoupper($word[0]);

    return $ret;

}

$st = initials($string);

$a = uniqid($st);

$b= substr($a, 0, 7);

echo $b ;

output: PSU1482