one way:

=SUM(IF(ISEMPTY(A1:A100),0,A1:A100))

this is an array-formula so CTRL+SHIFT+ENTER it instead of simply
using ENTER


On 11 Gru, 13:24, Jemma wrote:
Is there any way of only working out a sum in the boxes that are used and
discluding the boxes that haven't been used. For example i have a worksheet
which includes a column for discounts but it is not always used. Is there any
way it can recognise which cells have been used and only work out the sum
using those cells? Sorry if i dont make sense!