A column (A1:A3) includes positive numbers and B column (B4:B26) includes negative numbers; and they all exactly net-off to zero.

But excel comes out 2 different sum results if I try 2 SUM:

- SUM whole 2 ranges: =SUM(A1:B26); or =SUM(A1:A3,B4:B26) the answer is

**not exactly zero**. It is very small, but it is not acceptable.

- SUM of 2 separate SUM: =SUM(SUM(A1:A27),SUM(B1:B27)); or =SUM(A1:A27)+SUM(B1:B27) the answer is

**exactly zero**

In addition, the quick preview on bottom of excel shows the same result with SUM whole 2 ranges.

For sure, I have checked all decimal position. It is driving me crazy. Is there any way to solve this, anyone please help. Thank you in advance.