Power of Chaos allows you to see the number of cards left in your deck. Â I can't remember where the pictures for Yu-gi-oh online are.. but i believe it allowed the same. Â Keep in mind that one can always deduce the numbers of cards left by counting the cards in the graveyard, on the field, in the hand, under the opponents control, and in the removed from play pile. Â But late in the duel that might be considered stalling so counting the deck would make more sense.
However card sleeve are translucent and reflective, counting the cards might be considered an attempt to cheat.