You can always check your equipment to determine how many balls you have left in your bag. I have found that once you pick the balls you want to play with, it is best to stick with them, I try to buy 10 at a time so that I don't run out in a round, just check your bag every few days or once a week. The one negative that I have regarding balls is that they wear out too quickly, we should get more wear from them. It also seems that balls wear a lot more than they should during the CTTH play, I have noticed that a ball seems to wear almost as much as in a nine hole match during the 9 shots you hit in CTTH.