This is another of those "interesting" tech support cases (where "interesting" means painful and tedious). Our platform collects lots of data for our customers, and generates lots of nice juicy reports for them in an assortment of formats. Being a sensible developer, I'd done this using a typical MVC pattern, so there are models which get data out of the database, and then different views to format it into each report. The support case was that some numbers were being displayed with a ridiculous number of decimal places in Excel reports.