Now, are we done? Is this what the sample mean is? Well, no, we aren't done. We don't just add up all of the data points. We then have to divide by the number of data points there are. So we then have to divide, we then have to divide by the number of data points that there actually are. So this might look like very fancy notation, but it's really just saying, add up your data points and divide by the number of data points you have.