Serious Flaw In Microsoft Excel 2007 Displays Math Errors

Microsoft Excel 2007 has math problems. Over the weekend some folks in the Microsoft Excel Google Group reported that cell operations like =77.1*850 return erroneous results (in this case Excel returns the value as 100,000 when in fact it's 65,535). A post on the Excel Blog confirms the issue and even says the problem is more widespread than initially reported.

Fortunately the Excel team has identified the problem and is says it’s working on a solution. As it turn out, Excel can add, contrary to some headlines, it just doesn’t display the right data in the cell.

This issue was introduced when we were making changes to the Excel calculation logic in the Office 2007 time frame. Specifically, Excel incorrectly displays the result of a calculation in 12 very specific cases. The key here is that the issue is actually not in the calculation itself (the result of the calculation stored in Excel’s memory is correct), but only in the result that is shown in the sheet. Said another way, =850*77.1 will display an incorrect value, but if you then multiply the result by 2, you will get the correct answer (i.e. if A1 contains “=850*77.1”, and A2 contains “=A1*2”, A2 will return the correct answer of 131,070).

The Excel team says they have a fix for this issue and are almost done testing to ensure that the fix works and doesn’t introduce any additional issues. Once they’re satisfied an update will be made available.

Note that this issue does not affect earlier versions of Excel.