To populate blanks with zeroes in existing data follow these steps.
- Select the data range and press the F5 function key.
- Click the Special button.
- Click the Blanks option and click OK. This will select all the blank cells.
- Type 0 then hold the Ctrl key and press the Enter key. Release the keys.
- This will populate all the blank cells in the range with zeroes.
Warning: make sure you select the range as per step 1, otherwise you may populate blank cells in other parts of the sheet with a zero.