This is due to the fact there are ways of Hiding Data through the use of identically-colored fonts, empty-string results of a formula, or masking the data with the use of Custom Formatting (three semicolons: ;;; ). If you don’t know if a cell is Truly Blank, it can cause Mayhem with your calculations.
To detect this Invisible Data, there are at least a couple of techniques. Assuming your cell in question is A1, you can:
1. Simply insert this Function in an adjacent cell: =ISBLANK(A1)
a. If the cell is Blank, it will return True; if it is Not Blank, it will return False
2. Also use an IF Statement as follows: =IF(A1<>"","Not Blank", "Blank")
a. This IF Statement obviously returns Blank or Not Blank
By determining if your cells are Truly Blank, you can Avoid Problems on your worksheets, and I don’t know about you, but I think Avoiding Problems, Rocks!