The best way to do this is by converting your data to an Excel table. Select your data range (A1:E11), press Ctrl + T, and ...
The simplest way to think about SCAN is that it applies a custom calculation to each element in a range/array and returns every intermediate result it produces along the way. If that sounds abstract, ...
To add a formula in Google Sheets, click the cell where you want the answer, then choose one of the hundreds of functions.