"Andrew Taylor" wrote in
oups.com:

Actually it seems you _can_ (almost) do it, with number format
#,##0.############### (15 #s after the decimal point, which will
always be enough as Excel displays at most 15 digits precision).

The only drawback is that whole numbers display with a trailing
decimal point.

That has one other drawback besides the trailing decimal point. If the cell is
only wide enough to show (say) 3 decimal points, it either widens the column or
displays ###########.

Thanks for the suggetion, though.