Excel 2007 Bug

This is an interesting one.

Do the following:

Open up calculator and execute 850*77.1.

This should give you an answer of 65535.

Now open up Excel 2007 (if you have it of course).

In cell A1, create the following formula:

=850*77.1

For some reason, the answer is 100000.

Now this doesn't make sense at all, but it goes even deeper than that!

In A2, create a formula that says:

=A1+1

The result is 100001. But if you create the formula =A1-1 in cell A3, the result is 65534.

Even thinking like a programmer, this does not make any sense to me.

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Update from Computerworld

October 10, 2007 (Computerworld) Microsoft Corp. yesterday patched a bug in Excel 2007 that displayed wrong values for calculations around a pair of numbers, and said it would push the fixes through Windows Update as soon as possible.

The bug, which Microsoft acknowledged two weeks ago, displays 100,000 as the result of calculations that should instead show either 65,535 or 65,536. The error, Microsoft claimed last month, is not in Excel's calculations, but in the code that takes resulting values and formats them before they're displayed in a cell on the spreadsheet. Only the newest version, Excel 2007, and its online cousin, SharePoint's Excel Services 2007, contain the bug.

Fixes for the bug, as well as documentation logged into Microsoft's support database, have been posted to the company's download site, with links available on Microsoft's Excel blog. The download for Excel 2007 is a substantial 32.5MB.

"We are in the process of adding this fix to Microsoft Update so that it will get automatically pushed to users running Excel 2007 or Excel Services 2007," said David Gainer, the program's lead project manager, on the team's blog. The patch was not among the non-security updates included with yesterday's bulletins, however. Gainer also noted that the hotfix would be added to the first service pack for Office 2007, although Microsoft has said nothing about its work on Office 2007 SP1, or its release date.

The next regularly scheduled update is Nov. 13, but Microsoft has also taken to rolling out non-security hotfixes, especially for newer products such as Windows Vista, on the last Thursday of each month. This month, that day will be Oct. 25.

Interesting...

Strangely enough, there are still some other bugs that have been floating around for 10 years or more.

Enter any of the following formulas into a cell.
=40000.223
=41000.348
=52000.723

Such numbers are converted to:

=40000.2229999999
=41000.3479999999
=52000.7229999999

Maybe if the community makes a big enough noise (like with the multiplication bug) they might fix this one too?