Deleting items from your content set (for example, item numbers 3-5) leaves a gap in the content set item order (for example, 1, 2, 6, 7, 8...). For continuous content item numbering, you can renumber your content set by clicking Renumber on the Content Set menu.
You can also randomize the order of items in your content set. This is recommended prior to creating and analyzing a knowledge base, especially if items in the same category are grouped together (see Content item order).
You can choose to randomize the current content item order, or save a randomized copy of the current content set. Note that when you randomize the content set, the randomized version replaces the current content set.