Your assumption that no one has noticed is incorrect.
It is a common problem when adding numbers with many decimal points.
See John McGimpsey's site for explanation and workaround.
http://www.mcgimpsey.com/excel/pennyoff.html
Gord Dibben MS Excel MVP
On Tue, 1 Jun 2010 02:02:01 -0700, The Yeti
wrote:
Hi,
I take it no-one has come across this before then... I'll kee[p looking
around for something and post back if I find anything useful.