Depends. Do you roll a random number from a generator until it matches the displayed number? If yes, if you have 1,000,000 visitors per day, the probability o

Depends. Do you roll a random number from a generator until it matches the displayed number? If yes, if you have 1,000,000 visitors per day, the probability of having a winner is around 63 %. However, if your random number generator guarantees that each player gets a different number then yes, the probability of having a winner approaches 100% as you get closer to the millionth visitor.