How do we uh? If you watched the last one on how I cut out the corners, how we make the "X" and all that. And how do we find the center of this line, and this line and this line. It's roughly the same thing except for what we're going to do is, we're going to make a sphere. So, from here let's do what we learned already. Let's make an "X" to find the center of our box. So, what essentially will be the center of our sphere. Well, there's our center. And let's find the center that goes all the way around both boxes. All the whole box. So, bingo. There's our "X", all the way across. And this point will run all the way through to this side. So I should make one on the backside too. OK.