We have two lottery game with 1:1000 odds to win. I have money to buy 20 tickets. Q1. If I spend my money on one of these games only then I have 1:50 chance to win. Am I right? Q2. If I spend my money to buy 10-10 tickets and play both of games then I have 1:100 chance to win on the first and the same chance to win on the second game. But what is my chance to win at least one game this time? I have only 1:100 or 1:50 like in question Q1? If I split my money I split (reduce) my chance too?