Hi
I can't get it right, I've designed a database and designed a Scalextric
race track with all the part numbers in Column A, Qty in Column D, Current
Stock in Column F and to Buy in Column G.

This is what I have tried
=IF(F19=0,"",IF((D19-F19)<=0,"",D19-F19))

This works to a point, it does all the other things I wanted but does not
put the Qty required in Column G, it leaves that cell blank

Example I have
A D F G
C8235 15 blank blank

result should be 15 in Column G as I need 15 of Part C8235 for this track
and I'm showing none in stock in column F so column G should show 15 needed
to buy.

Another example
A D F G
C8205 70 9 61

result should be 61 in Column G

NOTE - if a part is not used result in column G should be blank