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Binary? Decimal? Excel 2007 finds it all so confusing

Excel 2007 has troubles with multiplication when the result is 65,535--a number familiar to those who've dealt with binary numbers.

Stephen Shankland principal writer
Stephen Shankland has been a reporter at CNET since 1998 and writes about processors, digital photography, AI, quantum computing, computer science, materials science, supercomputers, drones, browsers, 3D printing, USB, and new computing technology in general. He has a soft spot in his heart for standards groups and I/O interfaces. His first big scoop was about radioactive cat poop.
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Stephen Shankland
2 min read

Microsoft on Tuesday confirmed a bug in Excel 2007 that can cause it to produce erroneous answers for a particular multiplication task.

Specifically, the problem can crop up when the answer to a multiplication problem should result in 65,535. You fans of binary arithmetic don't need to be told that's 2 to the 16th power minus one, or maximum integer that can be described with two bytes, counting up from zero. So it's a good bet some binary-to-decimal translation is involved in the problem.

A repair is in the works, Microsoft said, without sharing much more in the way of detail.

"We are currently in the process of developing and testing a fix for the flaw," Microsoft said in a statement Tuesday. "Microsoft places a high priority on quickly responding to customer feedback, and we are committed to finding ways to provide a better software experience."

News of the bug surfaced Saturday on an Excel mailing list, and Slashdot picked it up Tuesday. The latter forum, with a disproportionate population of Microsoft bashers, gleefully pounced on the problem.

One commenter said Microsoft's fix will offer a new rendition of the hated Clippy: The fix will trigger the appearance of "an animated sprite of Charles Babbage's head," who will say, "It looks like you're trying to multiply two numbers. I can help show you how to use the Method of Finite Differences to find a good approximation of your answer using only addition and subtraction. Would you like me to bring up a wizard so that we can get started on finding an appropriate power series?"

Another commenter was more constructive, observing that even when the problem crops up, the correct results are placed in a graph.