If you have a range of cells, of which some contain values and some are blank, and you want to select just the blank cells, there is a quick way to select those blank cells that doesn't involve manually clicking on every one.
To do this, follow these steps:
Select the range of cells in your spreadsheet from which you want to select only the blank cells.
Press F5 on the keyboard. Note that this step works for any version of Excel on Windows or on a Mac with a full keyboard. If you have a Mac with function buttons, press FN+F5.
Then click the Special... button
Select the option for Blanks
Once you click OK, you'll find that only the blank cells in the range have been selected.
The main reason you might want to do this is to enter a value or formula into only the blank cells in a range. To find out how you can do this, see the lesson on how to Quickly enter a formula in multiple cells.