Hi there.
You may want to try:

=SUM(A10:A20)-IF(ISNUMBER(A5),A5,0)

Anyway, you should be sure that the value in A5 IS a number and not a
string/text that 'SEEMS' to be a number. Tip: text/string are left aligned by
default.

Regards,
Otávio

"mexmex" wrote:

Trying to total sum a range of cells in a column and subtract from a total in
another cell in the same column, getting a value error

ex sum cell a10 to a20 then subtract from the number in a5
excel 2007
--
Max