In a previous piece, I wrote about small businesses needing to consider using a variety of Open Source (or free) software programs to run their offices - it's often safer, more secure, more stable, and a lot cheaper.
Simply put the following formula in an Excel 2007 spreadsheet:
The proper answer is "65535" - try it for yourself to see what you get.
Don't make the mistake of thinking that this error will never affect you. Check out the list of additional bugs from the newsgroup piece.
There are plenty of bugs in the various M$ Office competitors, I am sure. I've found some of my own...but cell multiplication errors, especially one as basic as this one, are inexcusable. And, if it were an open source solution, someone would already have fixed it. For free.
I mention all this because I first switched to OpenOffice 6? 7? years ago when I spent a day trying to figure out why a cell wouldn't add up properly in Excel - only to have it all work properly the first time I opened it in OO. I haven't been back since.