Counts the number of empty cells in a range of cells in the whole workbook.
COUNTBLANK3D is very similar to the COUNTBLANK function of Microsoft Excel. The main difference is that COUNTBLANK3D considers all worksheets, while the original COUNTBLANK function doesn't.
range_input - is the range from which you want to count the empty cells.
include_current - Optional. Boolean argument , either TRUE or FALSE. Decides whether the current worksheet is included in the function's consideration. TRUE means the current worksheet will be considered, and vice versa.
Cells with formulas that return "" (empty text) are also counted. Cells with zero values are not counted.