1) Change your formula to add a condition so you don't get negative numbers:
=If(yourFormula<0,0,yourFormula)
You would need to put this into cells with existing formula that return
numbers <0. In place of 'yourFormula' in the above, substitute the existing
formula in you cell (without the equal sign).
Example if Cell C1 contained =A1-A2, your new formula would become
=IF(A1-A2<0,0,A1-A2)
2) Format cells with a custom format. The following will change the font
colour of negative numbers to white. Negative values will appear as a dash
in the cell. If you click on the cell, you can see the number in the
formula bar. Any dependant cell will have access to the hidden negative
number.
#,##0;-
If you don't wish to see the dash the customs format is
#,##0;
If you want a word:
#,##0;"negative"
3) VBA - avoid if possible
Sub SetNegToZero()
' warning if cell value is negative
' this will overwrite existing cell formula
Dim C
For Each C In Selection
If C.Value < 0 Then C.Value = 0
Next C
End Sub
