Hi

It returns -1 for me.
This is quite understandable. If you wanted the sum of the numbers as a
negative, then the formula should be =-SUM(A1:A5) which would return -15

Having the negative inside the bracket, causes Excel to apply the minus, but
only to the first cell in the range and then stop.
If you entered it as an array formula
{=SUM(-A1:A5)}
then Excel would return -15.
As an Array formula, Excel would make each cell negative in the range, prior
to summing them.

Array formulae are entered or edited using Control+Shift+Enter (CSE) not
just Enter.
When you use CSE, Excel inserts the curly braces { } around your
formula. Do not type them yourself.

--

Regards
Roger Govier

"mchazka" wrote in message
...
I accidently came across this function : sum(-a1:a5). Suppose cells a1:a5
contains 1,2,3,4,5. The returned value is -3. How does Excel derive this
value based on the formula?