Strange error in simple addition

[SammyH]

I have a very strange error in which a simple column of figures are adding
up incorrectly.

The figures are directly input figures(not dependents)
I have identified the figure concerned which is 200
It is adding up as 2000

If I cut paste the column into a new sheet the error continues to appear
If I cut paste as Values the offending figure of 200 pastes as 2000 (thus
identifying the error - It should appear as 200.00)
If I delete the original 200 and retype it in as 200 the error disappears
and the column adds correctly

The error appeared after we sent a tender in which consisted of 20 pages of
figures and we were told that our addition was wrong.
No amount of searching in Excel would highlight this error.
I used all trace precedents/dependents
I have checked that the figure has not got ant text formatting

I shudder to think the implications if this were to occur regularly.
Any ideas for checking this in the future.

I would consider myself a fairlyy advanced Excel user

Thanks

Sam

 

[Charles Williams]

Maybe the cell has some strange custom format applied:
check using Format Cells

regards
Charles

 

[Bruce Sinclair]

Maybe the cell has some strange custom format applied:
check using Format Cells

... or the cell could have an invisible character in it (eg some of the
control characters or those characters that show nothing if you look at the
character set) ? This sounds likely to me, as if you manually type 200 in,
that's what you see (yes ?) and that's what you get, and if you cut and
paste, the problem follows the cell around. To check, maybe turn it into
text and check the length of it ? If it's bigger than you think it should
be, that might be the problem ?

How to check a spreadsheet for those in future ... that's a bit harder.
You could probably use data validation when putting the thing together to
stop them ... but that isn't really a check to see if there are any.

Hope that helps a little.