Try to work out the exact binary representation for 372.58 and that will
give you a clue as to the reason. [Hint: there isn't an exact binary
representation for most decimal numbers, just as there isn't an exact
decimal representation for a number like =10/3. You're OK with 0.5 or 0.25,
but with 0.1 or 0.01]

Try =ROUND(A1-B1-C1,2) or rounding to whatever resolution you need.

More info at http://www.mcgimpsey.com/excel/pennyoff.html
--
David Biddulph

"flavio.c" wrote in message
...
Hi friends,

I have a simple question about calculation accuracy (excel 2002) that
drives me crazy: just enter in
A1 value 388
B1 value 372.58
C1 value 15.42

and then in a new cell the formula = A1 - B1 - C1

One would expect 0 as result, instead gets 1.59872E-14

Do you know why this occur? There is a way to force the result to 0
anyway?

Thanks a lot for any help or suggestion on this.

Ciao

Flavio