A more simpler way of making it provably fair, will be to just use the server seed and the client seed for the 60,300,000,000 bet and the next bet ids accordingly till all the winners are picked. In case of same numbers or If the bets are on either on hacker or cells game the next bet id is taken. Since the Last Entry Number will be 1 less than the total entries the numbering starts from 0.
$client_seed = 'clientseedofthebetidchosen';
$server_seed = 'serverseedofthebetidchosen';
$result_seed = hash_hmac('sha512', $server_seed, $client_seed);
$result_number = hexdec(substr($result_seed,0,10));
$lucky_number = abs($result_number % 100); // Instead of 100 Use Total Entries-1
Can be tested here: http://phptester.net/