It is a consequence of rounding numbers that cannot be exactly represented
in binary fashion. It is similar to the case of 1/3+1/3+1/3 < 1 with a
finite number of decimal places. No matter how many decimal places you use,
you'll always get 0.999..., not 1. Numbers are rounded at the very small
end. See www.cpearson.com/Excel/Rounding.htm for more details.


--
Cordially,
Chip Pearson
Microsoft MVP - Excel
Pearson Software Consulting
www.cpearson.com
(email on the web site)


"Chwan Keng Ng" wrote in message
...
I have a set of journal data extracted from SQL Server 2005 and paste them
in Excel 2003, the net result of this set of number should produce 0,
instead in the cell that I use the =SUM() function, it produced
"5.54365E-11"
How come?
I could format the cell using "Number" which gaved me "0" but I am just
wondering why?