I guess I've been causing the death of kittens for a while then. I couldn't, however, deduce from your wikipedia link or from a quick google search what the correct way of adding floating point numbers should be, though. Even the MS compiler guys at <a href="http://msdn.microsoft.com/en-us/library/aa289157%28VS.71%29.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/aa289157%28VS.71%29....</a> are writing code snippets that sum floating point numbers in a loop.<p>edit: You're write jfager. I didn't read the article I linked to very carefully. The article actually has an example algorithm, the Kahan sum, for reducing the error caused by summing floating point numbers in a loop!