As has been said already, no, you can't have more than 256 columns. It's
quite unusual to need that many columns. Tell us about your sheet, and
maybe there are ways to use less columns.
...
If it's so unusual to need so many columns, why is this question asked so
frequently? Why do the last 3 versions of Quattro Pro provide over 18,000
columns? Why do the native Unix/Linux/BSD commercial spreadsheets (Xess, NeXS,
Applixware) [other than StarOffice/OpenOffice, which wants to be close to Excel
in functionality] provide over 1000 columns?
Yes, there are work-arounds, but they're as efficient as transporting thousands
of tons of coal in sportscars.
It's one thing to be realistic and state that Excel only provides 256 columns
per worksheet. It's another to fail to understand that this is an *ARBITRARY*
limit.