As Gene said, you play it till you lose the bet. I've never seen them track the serial numbers on the smaller denominations, but I have seen Caesars Palace record the sn of some blue NCV's as they dropped them in the money slot. I believe they were $500 denominations, but don't remember for sure. The asian guy who played them was playing live $5000 chips, and losing consistently. When he had lost all his chips, he took a wad of $100's from his pocket and tossed them in the betting circle. The dealer asked the P.B. if he should spread and count it. The answer was "don't bother". He lost. Nineteen hundreds went down the slot, following about $50,000 in live chips. The player, who had remained standing for his 10 minutes at the BJ table, left saying "Don't worry, be happy!".