Sorting information in a Numbers spreadsheet can be really powerful for visualizing your data in a specific way. However, if you're not careful, it could cause you some problems. Here's an example of what I mean.
Let's say we have a spreadsheet of names and test scores. After the last student's test score, we want to add a row that contains test score averages, so that at the end of the school year, we can build a trend line for each test. If we sort the columns after we create the "Average" row, the sorting will include that row, mixing everything up for us. Believe it or not, the fix for this is super-easy, and is applicable to moe than just a spreadsheet full of test scores.
After we have added our "Averages" row, and we have added the calculations necessary to make that row functional and meaningful, all we need to do is to convert that row to a "Footer Row". To do this, we simply right-click on the header of a row and choose the "Convert to Footer Row" option.
Note: only the last row can be converted to a Footer Row.
A Footer Row is similar to a Header Row in that it is not taken into consideration when we perform a sorting operation. Numbers simply leaves it alone, and sorts on everything else.
To illustrate what I mean, I created a short video. In this video, we have our data. The first thing I will do (mainly as a refresher for you) is to quickly create a formula to calculate each of the average values. First, I will create the average on a per student basis, then I will create averages for each test.
Once we have created the formulas, we will perform a sort function BEFORE we have converted our last row to a Footer Row so that you can see the mistake. Next, we will convert the row to a Footer Row. Lastly, we will perform one more sort on the same column so we can see that the new Footer Row is nor sorted along with the data.