Microsoft Excel 2007 Calculation Issue

Update

Microsoft has now posted a hotfix package to its Web site that corrects this flaw in Excel 2007 and Excel Services 2007. The fix will be offered soon through Microsoft Update so that users can get the patch automatically without having to go to Microsoft's site.

In late September 2007, Microsoft confirmed that there is floating point issue involving calculations of numbers around 65,535 in Excel 2007. Some of you may be experiencing a deja vu moment. In 1994, Intel had an similar but unrelated floating point flaw in some of the early models of the original Pentium processors. Intel was heavily criticized for both the flaw and their handling of the matter. They ultimately recalled the defective processors.

Although Microsoft has confirmed the issue (see Microsoft's blog entry), as of early October they have yet to release a patch or a fix for the problem. The first reported example of the error in Excel 2007 was that the formula =77.1 * 850 would return the value of 100,000 instead of the correct answer of 65,535. Other calculations have since been identified that also create the error. The issue only exists in Excel 2007, not previous versions.

Our research shows that as of August 2007 the prevalence of Microsoft's Excel 2007 was just under 11% for PCs used in the home. Business use of the application was almost 9%. Obviously, Microsoft wants this problem resolved and will likely have a fix available in the near future. In the meantime, it might be prudent to perform a manual review of your spreadsheet's calculations.

Prevalence of Excel 2007 by Business vs. Home

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