<?php

$re = '/^(\D+)?([\d \t]+)(\D+)?$/m';
$str = 'from 8 000 packs
432534534
from 344454 packs
45054 packs
04 555
434654
54 564 packs
';

preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);

foreach ($matches as $matchgroup) 
{
    echo "before: ".$matchgroup[1]."\n";
    echo "number:".preg_replace('/\D/m','',$matchgroup[2])."\n";
    echo "after:".$matchgroup[3]."";
    echo "\n\n\n";
    
}

php?>