Any way to access "hidden" columns from an Excel spreadsheet?

I have a ".xlsx" file which has hidden columns in it. I have Numbers, but not Office/Excel. I really don't want to buy Office just for one file. So far as I can tell, Numbers simply deletes all the hidden columns -- or at least, the "unhide hidden items" stuff is all greyed out. If I manually hide a column, I can unhide "all" columns -- but that doesn't include the ones that were previously hidden.

Any suggestions? I mean, apart from "don't buy iWork"? :)