So if someone just says the mean, they're really referring to what we typically, in everyday language, call the average. Sometimes it's called the arithmetic mean because you'll learn that there's other ways of actually calculating a mean. But it's really you just sum up all of the numbers and you divide by the numbers there are. And so it's one way of measuring the central tendency, or the average, I guess we could say. So this is our mean. We want to average 23 plus 29. Or we want to sum 23 plus 29 plus 20 plus 32 plus 23 plus 21 plus 33 plus 25.