Tom’s Tutorials For Excel: Numbering a Dynamic List of Filled Items
For situations such as lists that change often, with blank cells between topics that must be clearly indexed or numbered, here’s a formula that can do the job.
In the picture, a list of Excel training topics is being compiled. Later, the list is revised, and in fact the list might be revised many times. The trick is to have a formula in column A that automatically numbers the Topics as they appear in column B.
The formula in cell A6 is
=IF(B6<>"",COUNTA($B$6:B6),"") which was copied down as needed. But that’s it…no programming code or array formulas, just a single formula that updates the sequential numbers in column A when a new topic is entered into column B.