And then we are taking those, and we are taking the sum, and we are defining a random variable in that way. So the natural question you might ask is, why are we doing this? What's so useful about defining random variables like this? It will become more apparent as we get a little bit deeper in probability. But the simple way of thinking about it is, as soon as you quantify outcomes, you can start to do a little bit more math on the outcomes. And you can start to use a little bit more mathematical notation on the outcome. So for example, if you cared about the probability that the sum of the upward faces after rolling 7 dice, if you cared about the probability that that sum is less than or equal to 30, the old way that you would have to have written it is the probability that the sum of, and you would have to write all of what I just wrote here, is less than or equal to 30.