One of the things that most puts me off from using spreadsheets is the difficulty of validating calculations. A very good friend of mine worked for a major aer

One of the things that most puts me off from using spreadsheets is the difficulty of validating calculations. A very good friend of mine worked for a major aerospace company that used Excel spreadsheets for almost all engineering. I'd say the biggest problem is that if you're doing important calculations in Excel, then you're completely ignorant of the last 40 years of research into defect reduction and detection in computer science. That ignorance is not completely unintentional either: there were a lot of people who literally pride themselves on not being like the dumb computer folks. Plus, if spreadsheets are your tool, you likely have very bad tools. So when you make a spreadsheet to run the power budget for satellite A, the obvious thing to do when satellite B comes up for development is to copy the spreadsheet containing the analysis from sat A, change the filename and bury it somewhere on the shared network drive. Then, if you find a defect in the spreadsheet, you have no way of tracking which copies have that same defect because they're scattered all over the shared drive. In any event, my friend found tons of bugs in spreadsheets, many of which were actually important. Probably the best bug involved a power budget for satellites that inverted electrical current so instead of comparing current to a max theoretical current value, it compared 1/current to the max value.