I put 1, 2, 3, 4, 5 in A1:A5
I put the same formula: =sum(-a1:a5) in B1:B5 (all the same formula).

I got
-1 in B1
-2 in B2
-3 in B3
-4 in B4
-5 in B5

I think it has something to do with implicit indexing--something that I try to
avoid at all costs.

Entering all the formulas using ctrl-shift-enter resulted in -15 (for all of
them).

mchazka wrote:

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?

--

Dave Peterson