So the first thing we want to do is figure out the median here. So the median's the middle number. I have one, two, three, four, five, six, seven, eight, nine numbers, so there's going to be just one middle number. I have an odd number of numbers here. And it's going to be the number that has four to the left and four to the right, and that middle number, the median, is going to be 10. Notice I have four to the left and four to the right. And the interquartile range is all about figuring out the difference between the middle of the first half and the middle of the second half.