|■ Choose a cell style such as DisplayFormulaNumbered.|
|■ Use Insert ▶ Automatic Numbering with a counter name such as Section.|
These cells are in DisplayFormulaNumbered style. DisplayFormulaNumbered style is available in the default stylesheet.
The input for each cell here is exactly the same, but the cells contain an element that displays as a progressively larger number as one goes through the notebook.