Again- he just knew the 18 cards left...not the order...
The “shoe” (autocorrect - Siri deserves coal in her stocking) is the setup at a blackjack table... stack of 6+ decks of cards and the plastic container that holds them.
so, I think y’all have the wrong idea (and the story didn’t help- gave poor language...).
All they were asking him to do was know all the card left in the shoot. Not in order- that’s impossible.