MS Excel is <i>absolutely</i> unfit for most scientific and engineering problems.<p>The spreadsheet GUI, lack of good version tracking/history, and eagerness to coerce data types and "correct" values makes it easy to introduce errors that will go unrecognized and propagated through calculations. Unfortunately this story just keeps repeating itself.<p>But all of this is just a secondary concern to Excel's real trouble: it's history of incorrectly implementing numerical and statistical procedures. One could plumb the depths of this topic for hours, but here are a few highlights: regression formula accepts illegal/nonsensical inputs (e.g. collinear predictors) and gives illegal/nonsensical outputs [0], variance/standard deviation change incorrectly with sample size [0], output of a paired t-test changes when missing values are included [0], formulas are mislabeled [0], v. 2007 gives very wrong answers to 11 of 27 tests in the NIST test suite used for statistical software benchmarks [1], the random number generator was broken as late as v. 2007 [1], and calculations relying on any of 12 particular floats display an incorrect result [2]. There are plenty of other issues mentioned in the links and elsewhere; if you're interested you'll have no trouble finding them.<p>Remember, friends don't let friends use Excel for science. :)<p>[0] <a href="http://people.stern.nyu.edu/jsimonof/classes/1305/pdf/excelreg.pdf" rel="nofollow">http://people.stern.nyu.edu/jsimonof/classes/1305/pdf/excelr...</a><p>[1] <a href="http://www.pages.drexel.edu/~bdm25/excel2007.pdf" rel="nofollow">http://www.pages.drexel.edu/~bdm25/excel2007.pdf</a><p>[2] <a href="https://blogs.office.com/2007/09/25/calculation-issue-update/" rel="nofollow">https://blogs.office.com/2007/09/25/calculation-issue-update...</a><p>Edit: clarify and add a new issue I became aware of while researching further.