Lottery selections - Australian Powerball
In a lottery, or a raffle, numbers are usually selected from a pool of possible values in such a way that once a number has been chosen, it is no longer possible for it to be picked again. For example the balls in a lotto machine are removed one at at time, and there is no way for the same number to be picked twice. Similarly in a raffle, winning tickets are drawn and then discarded so that the same ticket cannot win twice.
See here for mathematical information on lottery probabilities.
In the Australian Powerball, 7 balls are drawn from a set of 35, and an additional selection of 1 drawn from a set of 20 - you can use the tool below to generate a similar selection of numbers.
The probability of matching all 7+1 numbers in any one draw is one chance in 134,490,400.
You can choose another lottery here, or specify the number of balls to be drawn below.